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- // SPDX-License-Identifier: GPL-2.0
- /*
- * TTY driver for MIPS EJTAG Fast Debug Channels.
- *
- * Copyright (C) 2007-2015 Imagination Technologies Ltd
- */
- #include <linux/atomic.h>
- #include <linux/bitops.h>
- #include <linux/completion.h>
- #include <linux/console.h>
- #include <linux/delay.h>
- #include <linux/export.h>
- #include <linux/init.h>
- #include <linux/interrupt.h>
- #include <linux/kernel.h>
- #include <linux/kgdb.h>
- #include <linux/kthread.h>
- #include <linux/sched.h>
- #include <linux/serial.h>
- #include <linux/serial_core.h>
- #include <linux/slab.h>
- #include <linux/spinlock.h>
- #include <linux/string.h>
- #include <linux/timer.h>
- #include <linux/tty.h>
- #include <linux/tty_driver.h>
- #include <linux/tty_flip.h>
- #include <linux/uaccess.h>
- #include <asm/cdmm.h>
- #include <asm/irq.h>
- /* Register offsets */
- #define REG_FDACSR 0x00 /* FDC Access Control and Status Register */
- #define REG_FDCFG 0x08 /* FDC Configuration Register */
- #define REG_FDSTAT 0x10 /* FDC Status Register */
- #define REG_FDRX 0x18 /* FDC Receive Register */
- #define REG_FDTX(N) (0x20+0x8*(N)) /* FDC Transmit Register n (0..15) */
- /* Register fields */
- #define REG_FDCFG_TXINTTHRES_SHIFT 18
- #define REG_FDCFG_TXINTTHRES (0x3 << REG_FDCFG_TXINTTHRES_SHIFT)
- #define REG_FDCFG_TXINTTHRES_DISABLED (0x0 << REG_FDCFG_TXINTTHRES_SHIFT)
- #define REG_FDCFG_TXINTTHRES_EMPTY (0x1 << REG_FDCFG_TXINTTHRES_SHIFT)
- #define REG_FDCFG_TXINTTHRES_NOTFULL (0x2 << REG_FDCFG_TXINTTHRES_SHIFT)
- #define REG_FDCFG_TXINTTHRES_NEAREMPTY (0x3 << REG_FDCFG_TXINTTHRES_SHIFT)
- #define REG_FDCFG_RXINTTHRES_SHIFT 16
- #define REG_FDCFG_RXINTTHRES (0x3 << REG_FDCFG_RXINTTHRES_SHIFT)
- #define REG_FDCFG_RXINTTHRES_DISABLED (0x0 << REG_FDCFG_RXINTTHRES_SHIFT)
- #define REG_FDCFG_RXINTTHRES_FULL (0x1 << REG_FDCFG_RXINTTHRES_SHIFT)
- #define REG_FDCFG_RXINTTHRES_NOTEMPTY (0x2 << REG_FDCFG_RXINTTHRES_SHIFT)
- #define REG_FDCFG_RXINTTHRES_NEARFULL (0x3 << REG_FDCFG_RXINTTHRES_SHIFT)
- #define REG_FDCFG_TXFIFOSIZE_SHIFT 8
- #define REG_FDCFG_TXFIFOSIZE (0xff << REG_FDCFG_TXFIFOSIZE_SHIFT)
- #define REG_FDCFG_RXFIFOSIZE_SHIFT 0
- #define REG_FDCFG_RXFIFOSIZE (0xff << REG_FDCFG_RXFIFOSIZE_SHIFT)
- #define REG_FDSTAT_TXCOUNT_SHIFT 24
- #define REG_FDSTAT_TXCOUNT (0xff << REG_FDSTAT_TXCOUNT_SHIFT)
- #define REG_FDSTAT_RXCOUNT_SHIFT 16
- #define REG_FDSTAT_RXCOUNT (0xff << REG_FDSTAT_RXCOUNT_SHIFT)
- #define REG_FDSTAT_RXCHAN_SHIFT 4
- #define REG_FDSTAT_RXCHAN (0xf << REG_FDSTAT_RXCHAN_SHIFT)
- #define REG_FDSTAT_RXE BIT(3) /* Rx Empty */
- #define REG_FDSTAT_RXF BIT(2) /* Rx Full */
- #define REG_FDSTAT_TXE BIT(1) /* Tx Empty */
- #define REG_FDSTAT_TXF BIT(0) /* Tx Full */
- /* Default channel for the early console */
- #define CONSOLE_CHANNEL 1
- #define NUM_TTY_CHANNELS 16
- #define RX_BUF_SIZE 1024
- /*
- * When the IRQ is unavailable, the FDC state must be polled for incoming data
- * and space becoming available in TX FIFO.
- */
- #define FDC_TTY_POLL (HZ / 50)
- struct mips_ejtag_fdc_tty;
- /**
- * struct mips_ejtag_fdc_tty_port - Wrapper struct for FDC tty_port.
- * @port: TTY port data
- * @driver: TTY driver.
- * @rx_lock: Lock for rx_buf.
- * This protects between the hard interrupt and user
- * context. It's also held during read SWITCH operations.
- * @rx_buf: Read buffer.
- * @xmit_lock: Lock for xmit_*, and port.xmit_buf.
- * This protects between user context and kernel thread.
- * It is used from chars_in_buffer()/write_room() TTY
- * callbacks which are used during wait operations, so a
- * mutex is unsuitable.
- * @xmit_cnt: Size of xmit buffer contents.
- * @xmit_head: Head of xmit buffer where data is written.
- * @xmit_tail: Tail of xmit buffer where data is read.
- * @xmit_empty: Completion for xmit buffer being empty.
- */
- struct mips_ejtag_fdc_tty_port {
- struct tty_port port;
- struct mips_ejtag_fdc_tty *driver;
- raw_spinlock_t rx_lock;
- void *rx_buf;
- spinlock_t xmit_lock;
- unsigned int xmit_cnt;
- unsigned int xmit_head;
- unsigned int xmit_tail;
- struct completion xmit_empty;
- };
- /**
- * struct mips_ejtag_fdc_tty - Driver data for FDC as a whole.
- * @dev: FDC device (for dev_*() logging).
- * @driver: TTY driver.
- * @cpu: CPU number for this FDC.
- * @fdc_name: FDC name (not for base of channel names).
- * @driver_name: Base of driver name.
- * @ports: Per-channel data.
- * @waitqueue: Wait queue for waiting for TX data, or for space in TX
- * FIFO.
- * @lock: Lock to protect FDCFG (interrupt enable).
- * @thread: KThread for writing out data to FDC.
- * @reg: FDC registers.
- * @tx_fifo: TX FIFO size.
- * @xmit_size: Size of each port's xmit buffer.
- * @xmit_total: Total number of bytes (from all ports) to transmit.
- * @xmit_next: Next port number to transmit from (round robin).
- * @xmit_full: Indicates TX FIFO is full, we're waiting for space.
- * @irq: IRQ number (negative if no IRQ).
- * @removing: Indicates the device is being removed and @poll_timer
- * should not be restarted.
- * @poll_timer: Timer for polling for interrupt events when @irq < 0.
- * @sysrq_pressed: Whether the magic sysrq key combination has been
- * detected. See mips_ejtag_fdc_handle().
- */
- struct mips_ejtag_fdc_tty {
- struct device *dev;
- struct tty_driver *driver;
- unsigned int cpu;
- char fdc_name[16];
- char driver_name[16];
- struct mips_ejtag_fdc_tty_port ports[NUM_TTY_CHANNELS];
- wait_queue_head_t waitqueue;
- raw_spinlock_t lock;
- struct task_struct *thread;
- void __iomem *reg;
- u8 tx_fifo;
- unsigned int xmit_size;
- atomic_t xmit_total;
- unsigned int xmit_next;
- bool xmit_full;
- int irq;
- bool removing;
- struct timer_list poll_timer;
- #ifdef CONFIG_MAGIC_SYSRQ
- bool sysrq_pressed;
- #endif
- };
- /* Hardware access */
- static inline void mips_ejtag_fdc_write(struct mips_ejtag_fdc_tty *priv,
- unsigned int offs, unsigned int data)
- {
- __raw_writel(data, priv->reg + offs);
- }
- static inline unsigned int mips_ejtag_fdc_read(struct mips_ejtag_fdc_tty *priv,
- unsigned int offs)
- {
- return __raw_readl(priv->reg + offs);
- }
- /* Encoding of byte stream in FDC words */
- /**
- * struct fdc_word - FDC word encoding some number of bytes of data.
- * @word: Raw FDC word.
- * @bytes: Number of bytes encoded by @word.
- */
- struct fdc_word {
- u32 word;
- unsigned int bytes;
- };
- /*
- * This is a compact encoding which allows every 1 byte, 2 byte, and 3 byte
- * sequence to be encoded in a single word, while allowing the majority of 4
- * byte sequences (including all ASCII and common binary data) to be encoded in
- * a single word too.
- * _______________________ _____________
- * | FDC Word | |
- * |31-24|23-16|15-8 | 7-0 | Bytes |
- * |_____|_____|_____|_____|_____________|
- * | | | | | |
- * |0x80 |0x80 |0x80 | WW | WW |
- * |0x81 |0x81 | XX | WW | WW XX |
- * |0x82 | YY | XX | WW | WW XX YY |
- * | ZZ | YY | XX | WW | WW XX YY ZZ |
- * |_____|_____|_____|_____|_____________|
- *
- * Note that the 4-byte encoding can only be used where none of the other 3
- * encodings match, otherwise it must fall back to the 3 byte encoding.
- */
- /* ranges >= 1 && sizes[0] >= 1 */
- static struct fdc_word mips_ejtag_fdc_encode(const char **ptrs,
- unsigned int *sizes,
- unsigned int ranges)
- {
- struct fdc_word word = { 0, 0 };
- const char **ptrs_end = ptrs + ranges;
- for (; ptrs < ptrs_end; ++ptrs) {
- const char *ptr = *(ptrs++);
- const char *end = ptr + *(sizes++);
- for (; ptr < end; ++ptr) {
- word.word |= (u8)*ptr << (8*word.bytes);
- ++word.bytes;
- if (word.bytes == 4)
- goto done;
- }
- }
- done:
- /* Choose the appropriate encoding */
- switch (word.bytes) {
- case 4:
- /* 4 byte encoding, but don't match the 1-3 byte encodings */
- if ((word.word >> 8) != 0x808080 &&
- (word.word >> 16) != 0x8181 &&
- (word.word >> 24) != 0x82)
- break;
- /* Fall back to a 3 byte encoding */
- word.bytes = 3;
- word.word &= 0x00ffffff;
- fallthrough;
- case 3:
- /* 3 byte encoding */
- word.word |= 0x82000000;
- break;
- case 2:
- /* 2 byte encoding */
- word.word |= 0x81810000;
- break;
- case 1:
- /* 1 byte encoding */
- word.word |= 0x80808000;
- break;
- }
- return word;
- }
- static unsigned int mips_ejtag_fdc_decode(u32 word, char *buf)
- {
- buf[0] = (u8)word;
- word >>= 8;
- if (word == 0x808080)
- return 1;
- buf[1] = (u8)word;
- word >>= 8;
- if (word == 0x8181)
- return 2;
- buf[2] = (u8)word;
- word >>= 8;
- if (word == 0x82)
- return 3;
- buf[3] = (u8)word;
- return 4;
- }
- /* Console operations */
- /**
- * struct mips_ejtag_fdc_console - Wrapper struct for FDC consoles.
- * @cons: Console object.
- * @tty_drv: TTY driver associated with this console.
- * @lock: Lock to protect concurrent access to other fields.
- * This is raw because it may be used very early.
- * @initialised: Whether the console is initialised.
- * @regs: Registers base address for each CPU.
- */
- struct mips_ejtag_fdc_console {
- struct console cons;
- struct tty_driver *tty_drv;
- raw_spinlock_t lock;
- bool initialised;
- void __iomem *regs[NR_CPUS];
- };
- /* Low level console write shared by early console and normal console */
- static void mips_ejtag_fdc_console_write(struct console *c, const char *s,
- unsigned int count)
- {
- struct mips_ejtag_fdc_console *cons =
- container_of(c, struct mips_ejtag_fdc_console, cons);
- void __iomem *regs;
- struct fdc_word word;
- unsigned long flags;
- unsigned int i, buf_len, cpu;
- bool done_cr = false;
- char buf[4];
- const char *buf_ptr = buf;
- /* Number of bytes of input data encoded up to each byte in buf */
- u8 inc[4];
- local_irq_save(flags);
- cpu = smp_processor_id();
- regs = cons->regs[cpu];
- /* First console output on this CPU? */
- if (!regs) {
- regs = mips_cdmm_early_probe(0xfd);
- cons->regs[cpu] = regs;
- }
- /* Already tried and failed to find FDC on this CPU? */
- if (IS_ERR(regs))
- goto out;
- while (count) {
- /*
- * Copy the next few characters to a buffer so we can inject
- * carriage returns before newlines.
- */
- for (buf_len = 0, i = 0; buf_len < 4 && i < count; ++buf_len) {
- if (s[i] == '\n' && !done_cr) {
- buf[buf_len] = '\r';
- done_cr = true;
- } else {
- buf[buf_len] = s[i];
- done_cr = false;
- ++i;
- }
- inc[buf_len] = i;
- }
- word = mips_ejtag_fdc_encode(&buf_ptr, &buf_len, 1);
- count -= inc[word.bytes - 1];
- s += inc[word.bytes - 1];
- /* Busy wait until there's space in fifo */
- while (__raw_readl(regs + REG_FDSTAT) & REG_FDSTAT_TXF)
- ;
- __raw_writel(word.word, regs + REG_FDTX(c->index));
- }
- out:
- local_irq_restore(flags);
- }
- static struct tty_driver *mips_ejtag_fdc_console_device(struct console *c,
- int *index)
- {
- struct mips_ejtag_fdc_console *cons =
- container_of(c, struct mips_ejtag_fdc_console, cons);
- *index = c->index;
- return cons->tty_drv;
- }
- /* Initialise an FDC console (early or normal */
- static int __init mips_ejtag_fdc_console_init(struct mips_ejtag_fdc_console *c)
- {
- void __iomem *regs;
- unsigned long flags;
- int ret = 0;
- raw_spin_lock_irqsave(&c->lock, flags);
- /* Don't init twice */
- if (c->initialised)
- goto out;
- /* Look for the FDC device */
- regs = mips_cdmm_early_probe(0xfd);
- if (IS_ERR(regs)) {
- ret = PTR_ERR(regs);
- goto out;
- }
- c->initialised = true;
- c->regs[smp_processor_id()] = regs;
- register_console(&c->cons);
- out:
- raw_spin_unlock_irqrestore(&c->lock, flags);
- return ret;
- }
- static struct mips_ejtag_fdc_console mips_ejtag_fdc_con = {
- .cons = {
- .name = "fdc",
- .write = mips_ejtag_fdc_console_write,
- .device = mips_ejtag_fdc_console_device,
- .flags = CON_PRINTBUFFER,
- .index = -1,
- },
- .lock = __RAW_SPIN_LOCK_UNLOCKED(mips_ejtag_fdc_con.lock),
- };
- /* TTY RX/TX operations */
- /**
- * mips_ejtag_fdc_put_chan() - Write out a block of channel data.
- * @priv: Pointer to driver private data.
- * @chan: Channel number.
- *
- * Write a single block of data out to the debug adapter. If the circular buffer
- * is wrapped then only the first block is written.
- *
- * Returns: The number of bytes that were written.
- */
- static unsigned int mips_ejtag_fdc_put_chan(struct mips_ejtag_fdc_tty *priv,
- unsigned int chan)
- {
- struct mips_ejtag_fdc_tty_port *dport;
- struct tty_struct *tty;
- const char *ptrs[2];
- unsigned int sizes[2] = { 0 };
- struct fdc_word word = { .bytes = 0 };
- unsigned long flags;
- dport = &priv->ports[chan];
- spin_lock(&dport->xmit_lock);
- if (dport->xmit_cnt) {
- ptrs[0] = dport->port.xmit_buf + dport->xmit_tail;
- sizes[0] = min_t(unsigned int,
- priv->xmit_size - dport->xmit_tail,
- dport->xmit_cnt);
- ptrs[1] = dport->port.xmit_buf;
- sizes[1] = dport->xmit_cnt - sizes[0];
- word = mips_ejtag_fdc_encode(ptrs, sizes, 1 + !!sizes[1]);
- dev_dbg(priv->dev, "%s%u: out %08x: \"%*pE%*pE\"\n",
- priv->driver_name, chan, word.word,
- min_t(int, word.bytes, sizes[0]), ptrs[0],
- max_t(int, 0, word.bytes - sizes[0]), ptrs[1]);
- local_irq_save(flags);
- /* Maybe we raced with the console and TX FIFO is full */
- if (mips_ejtag_fdc_read(priv, REG_FDSTAT) & REG_FDSTAT_TXF)
- word.bytes = 0;
- else
- mips_ejtag_fdc_write(priv, REG_FDTX(chan), word.word);
- local_irq_restore(flags);
- dport->xmit_cnt -= word.bytes;
- if (!dport->xmit_cnt) {
- /* Reset pointers to avoid wraps */
- dport->xmit_head = 0;
- dport->xmit_tail = 0;
- complete(&dport->xmit_empty);
- } else {
- dport->xmit_tail += word.bytes;
- if (dport->xmit_tail >= priv->xmit_size)
- dport->xmit_tail -= priv->xmit_size;
- }
- atomic_sub(word.bytes, &priv->xmit_total);
- }
- spin_unlock(&dport->xmit_lock);
- /* If we've made more data available, wake up tty */
- if (sizes[0] && word.bytes) {
- tty = tty_port_tty_get(&dport->port);
- if (tty) {
- tty_wakeup(tty);
- tty_kref_put(tty);
- }
- }
- return word.bytes;
- }
- /**
- * mips_ejtag_fdc_put() - Kernel thread to write out channel data to FDC.
- * @arg: Driver pointer.
- *
- * This kernel thread runs while @priv->xmit_total != 0, and round robins the
- * channels writing out blocks of buffered data to the FDC TX FIFO.
- */
- static int mips_ejtag_fdc_put(void *arg)
- {
- struct mips_ejtag_fdc_tty *priv = arg;
- struct mips_ejtag_fdc_tty_port *dport;
- unsigned int ret;
- u32 cfg;
- __set_current_state(TASK_RUNNING);
- while (!kthread_should_stop()) {
- /* Wait for data to actually write */
- wait_event_interruptible(priv->waitqueue,
- atomic_read(&priv->xmit_total) ||
- kthread_should_stop());
- if (kthread_should_stop())
- break;
- /* Wait for TX FIFO space to write data */
- raw_spin_lock_irq(&priv->lock);
- if (mips_ejtag_fdc_read(priv, REG_FDSTAT) & REG_FDSTAT_TXF) {
- priv->xmit_full = true;
- if (priv->irq >= 0) {
- /* Enable TX interrupt */
- cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
- cfg &= ~REG_FDCFG_TXINTTHRES;
- cfg |= REG_FDCFG_TXINTTHRES_NOTFULL;
- mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
- }
- }
- raw_spin_unlock_irq(&priv->lock);
- wait_event_interruptible(priv->waitqueue,
- !(mips_ejtag_fdc_read(priv, REG_FDSTAT)
- & REG_FDSTAT_TXF) ||
- kthread_should_stop());
- if (kthread_should_stop())
- break;
- /* Find next channel with data to output */
- for (;;) {
- dport = &priv->ports[priv->xmit_next];
- spin_lock(&dport->xmit_lock);
- ret = dport->xmit_cnt;
- spin_unlock(&dport->xmit_lock);
- if (ret)
- break;
- /* Round robin */
- ++priv->xmit_next;
- if (priv->xmit_next >= NUM_TTY_CHANNELS)
- priv->xmit_next = 0;
- }
- /* Try writing data to the chosen channel */
- ret = mips_ejtag_fdc_put_chan(priv, priv->xmit_next);
- /*
- * If anything was output, move on to the next channel so as not
- * to starve other channels.
- */
- if (ret) {
- ++priv->xmit_next;
- if (priv->xmit_next >= NUM_TTY_CHANNELS)
- priv->xmit_next = 0;
- }
- }
- return 0;
- }
- /**
- * mips_ejtag_fdc_handle() - Handle FDC events.
- * @priv: Pointer to driver private data.
- *
- * Handle FDC events, such as new incoming data which needs draining out of the
- * RX FIFO and feeding into the appropriate TTY ports, and space becoming
- * available in the TX FIFO which would allow more data to be written out.
- */
- static void mips_ejtag_fdc_handle(struct mips_ejtag_fdc_tty *priv)
- {
- struct mips_ejtag_fdc_tty_port *dport;
- unsigned int stat, channel, data, cfg, i, flipped;
- int len;
- char buf[4];
- for (;;) {
- /* Find which channel the next FDC word is destined for */
- stat = mips_ejtag_fdc_read(priv, REG_FDSTAT);
- if (stat & REG_FDSTAT_RXE)
- break;
- channel = (stat & REG_FDSTAT_RXCHAN) >> REG_FDSTAT_RXCHAN_SHIFT;
- dport = &priv->ports[channel];
- /* Read out the FDC word, decode it, and pass to tty layer */
- raw_spin_lock(&dport->rx_lock);
- data = mips_ejtag_fdc_read(priv, REG_FDRX);
- len = mips_ejtag_fdc_decode(data, buf);
- dev_dbg(priv->dev, "%s%u: in %08x: \"%*pE\"\n",
- priv->driver_name, channel, data, len, buf);
- flipped = 0;
- for (i = 0; i < len; ++i) {
- #ifdef CONFIG_MAGIC_SYSRQ
- #ifdef CONFIG_MIPS_EJTAG_FDC_KGDB
- /* Support just Ctrl+C with KGDB channel */
- if (channel == CONFIG_MIPS_EJTAG_FDC_KGDB_CHAN) {
- if (buf[i] == '\x03') { /* ^C */
- handle_sysrq('g');
- continue;
- }
- }
- #endif
- /* Support Ctrl+O for console channel */
- if (channel == mips_ejtag_fdc_con.cons.index) {
- if (buf[i] == '\x0f') { /* ^O */
- priv->sysrq_pressed =
- !priv->sysrq_pressed;
- if (priv->sysrq_pressed)
- continue;
- } else if (priv->sysrq_pressed) {
- handle_sysrq(buf[i]);
- priv->sysrq_pressed = false;
- continue;
- }
- }
- #endif /* CONFIG_MAGIC_SYSRQ */
- /* Check the port isn't being shut down */
- if (!dport->rx_buf)
- continue;
- flipped += tty_insert_flip_char(&dport->port, buf[i],
- TTY_NORMAL);
- }
- if (flipped)
- tty_flip_buffer_push(&dport->port);
- raw_spin_unlock(&dport->rx_lock);
- }
- /* If TX FIFO no longer full we may be able to write more data */
- raw_spin_lock(&priv->lock);
- if (priv->xmit_full && !(stat & REG_FDSTAT_TXF)) {
- priv->xmit_full = false;
- /* Disable TX interrupt */
- cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
- cfg &= ~REG_FDCFG_TXINTTHRES;
- cfg |= REG_FDCFG_TXINTTHRES_DISABLED;
- mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
- /* Wait the kthread so it can try writing more data */
- wake_up_interruptible(&priv->waitqueue);
- }
- raw_spin_unlock(&priv->lock);
- }
- /**
- * mips_ejtag_fdc_isr() - Interrupt handler.
- * @irq: IRQ number.
- * @dev_id: Pointer to driver private data.
- *
- * This is the interrupt handler, used when interrupts are enabled.
- *
- * It simply triggers the common FDC handler code.
- *
- * Returns: IRQ_HANDLED if an FDC interrupt was pending.
- * IRQ_NONE otherwise.
- */
- static irqreturn_t mips_ejtag_fdc_isr(int irq, void *dev_id)
- {
- struct mips_ejtag_fdc_tty *priv = dev_id;
- /*
- * We're not using proper per-cpu IRQs, so we must be careful not to
- * handle IRQs on CPUs we're not interested in.
- *
- * Ideally proper per-cpu IRQ handlers could be used, but that doesn't
- * fit well with the whole sharing of the main CPU IRQ lines. When we
- * have something with a GIC that routes the FDC IRQs (i.e. no sharing
- * between handlers) then support could be added more easily.
- */
- if (smp_processor_id() != priv->cpu)
- return IRQ_NONE;
- /* If no FDC interrupt pending, it wasn't for us */
- if (!(read_c0_cause() & CAUSEF_FDCI))
- return IRQ_NONE;
- mips_ejtag_fdc_handle(priv);
- return IRQ_HANDLED;
- }
- /**
- * mips_ejtag_fdc_tty_timer() - Poll FDC for incoming data.
- * @opaque: Pointer to driver private data.
- *
- * This is the timer handler for when interrupts are disabled and polling the
- * FDC state is required.
- *
- * It simply triggers the common FDC handler code and arranges for further
- * polling.
- */
- static void mips_ejtag_fdc_tty_timer(struct timer_list *t)
- {
- struct mips_ejtag_fdc_tty *priv = from_timer(priv, t, poll_timer);
- mips_ejtag_fdc_handle(priv);
- if (!priv->removing)
- mod_timer(&priv->poll_timer, jiffies + FDC_TTY_POLL);
- }
- /* TTY Port operations */
- static int mips_ejtag_fdc_tty_port_activate(struct tty_port *port,
- struct tty_struct *tty)
- {
- struct mips_ejtag_fdc_tty_port *dport =
- container_of(port, struct mips_ejtag_fdc_tty_port, port);
- void *rx_buf;
- /* Allocate the buffer we use for writing data */
- if (tty_port_alloc_xmit_buf(port) < 0)
- goto err;
- /* Allocate the buffer we use for reading data */
- rx_buf = kzalloc(RX_BUF_SIZE, GFP_KERNEL);
- if (!rx_buf)
- goto err_free_xmit;
- raw_spin_lock_irq(&dport->rx_lock);
- dport->rx_buf = rx_buf;
- raw_spin_unlock_irq(&dport->rx_lock);
- return 0;
- err_free_xmit:
- tty_port_free_xmit_buf(port);
- err:
- return -ENOMEM;
- }
- static void mips_ejtag_fdc_tty_port_shutdown(struct tty_port *port)
- {
- struct mips_ejtag_fdc_tty_port *dport =
- container_of(port, struct mips_ejtag_fdc_tty_port, port);
- struct mips_ejtag_fdc_tty *priv = dport->driver;
- void *rx_buf;
- unsigned int count;
- spin_lock(&dport->xmit_lock);
- count = dport->xmit_cnt;
- spin_unlock(&dport->xmit_lock);
- if (count) {
- /*
- * There's still data to write out, so wake and wait for the
- * writer thread to drain the buffer.
- */
- wake_up_interruptible(&priv->waitqueue);
- wait_for_completion(&dport->xmit_empty);
- }
- /* Null the read buffer (timer could still be running!) */
- raw_spin_lock_irq(&dport->rx_lock);
- rx_buf = dport->rx_buf;
- dport->rx_buf = NULL;
- raw_spin_unlock_irq(&dport->rx_lock);
- /* Free the read buffer */
- kfree(rx_buf);
- /* Free the write buffer */
- tty_port_free_xmit_buf(port);
- }
- static const struct tty_port_operations mips_ejtag_fdc_tty_port_ops = {
- .activate = mips_ejtag_fdc_tty_port_activate,
- .shutdown = mips_ejtag_fdc_tty_port_shutdown,
- };
- /* TTY operations */
- static int mips_ejtag_fdc_tty_install(struct tty_driver *driver,
- struct tty_struct *tty)
- {
- struct mips_ejtag_fdc_tty *priv = driver->driver_state;
- tty->driver_data = &priv->ports[tty->index];
- return tty_port_install(&priv->ports[tty->index].port, driver, tty);
- }
- static int mips_ejtag_fdc_tty_open(struct tty_struct *tty, struct file *filp)
- {
- return tty_port_open(tty->port, tty, filp);
- }
- static void mips_ejtag_fdc_tty_close(struct tty_struct *tty, struct file *filp)
- {
- return tty_port_close(tty->port, tty, filp);
- }
- static void mips_ejtag_fdc_tty_hangup(struct tty_struct *tty)
- {
- struct mips_ejtag_fdc_tty_port *dport = tty->driver_data;
- struct mips_ejtag_fdc_tty *priv = dport->driver;
- /* Drop any data in the xmit buffer */
- spin_lock(&dport->xmit_lock);
- if (dport->xmit_cnt) {
- atomic_sub(dport->xmit_cnt, &priv->xmit_total);
- dport->xmit_cnt = 0;
- dport->xmit_head = 0;
- dport->xmit_tail = 0;
- complete(&dport->xmit_empty);
- }
- spin_unlock(&dport->xmit_lock);
- tty_port_hangup(tty->port);
- }
- static int mips_ejtag_fdc_tty_write(struct tty_struct *tty,
- const unsigned char *buf, int total)
- {
- int count, block;
- struct mips_ejtag_fdc_tty_port *dport = tty->driver_data;
- struct mips_ejtag_fdc_tty *priv = dport->driver;
- /*
- * Write to output buffer.
- *
- * The reason that we asynchronously write the buffer is because if we
- * were to write the buffer synchronously then because the channels are
- * per-CPU the buffer would be written to the channel of whatever CPU
- * we're running on.
- *
- * What we actually want to happen is have all input and output done on
- * one CPU.
- */
- spin_lock(&dport->xmit_lock);
- /* Work out how many bytes we can write to the xmit buffer */
- total = min(total, (int)(priv->xmit_size - dport->xmit_cnt));
- atomic_add(total, &priv->xmit_total);
- dport->xmit_cnt += total;
- /* Write the actual bytes (may need splitting if it wraps) */
- for (count = total; count; count -= block) {
- block = min(count, (int)(priv->xmit_size - dport->xmit_head));
- memcpy(dport->port.xmit_buf + dport->xmit_head, buf, block);
- dport->xmit_head += block;
- if (dport->xmit_head >= priv->xmit_size)
- dport->xmit_head -= priv->xmit_size;
- buf += block;
- }
- count = dport->xmit_cnt;
- /* Xmit buffer no longer empty? */
- if (count)
- reinit_completion(&dport->xmit_empty);
- spin_unlock(&dport->xmit_lock);
- /* Wake up the kthread */
- if (total)
- wake_up_interruptible(&priv->waitqueue);
- return total;
- }
- static int mips_ejtag_fdc_tty_write_room(struct tty_struct *tty)
- {
- struct mips_ejtag_fdc_tty_port *dport = tty->driver_data;
- struct mips_ejtag_fdc_tty *priv = dport->driver;
- int room;
- /* Report the space in the xmit buffer */
- spin_lock(&dport->xmit_lock);
- room = priv->xmit_size - dport->xmit_cnt;
- spin_unlock(&dport->xmit_lock);
- return room;
- }
- static int mips_ejtag_fdc_tty_chars_in_buffer(struct tty_struct *tty)
- {
- struct mips_ejtag_fdc_tty_port *dport = tty->driver_data;
- int chars;
- /* Report the number of bytes in the xmit buffer */
- spin_lock(&dport->xmit_lock);
- chars = dport->xmit_cnt;
- spin_unlock(&dport->xmit_lock);
- return chars;
- }
- static const struct tty_operations mips_ejtag_fdc_tty_ops = {
- .install = mips_ejtag_fdc_tty_install,
- .open = mips_ejtag_fdc_tty_open,
- .close = mips_ejtag_fdc_tty_close,
- .hangup = mips_ejtag_fdc_tty_hangup,
- .write = mips_ejtag_fdc_tty_write,
- .write_room = mips_ejtag_fdc_tty_write_room,
- .chars_in_buffer = mips_ejtag_fdc_tty_chars_in_buffer,
- };
- int __weak get_c0_fdc_int(void)
- {
- return -1;
- }
- static int mips_ejtag_fdc_tty_probe(struct mips_cdmm_device *dev)
- {
- int ret, nport;
- struct mips_ejtag_fdc_tty_port *dport;
- struct mips_ejtag_fdc_tty *priv;
- struct tty_driver *driver;
- unsigned int cfg, tx_fifo;
- priv = devm_kzalloc(&dev->dev, sizeof(*priv), GFP_KERNEL);
- if (!priv)
- return -ENOMEM;
- priv->cpu = dev->cpu;
- priv->dev = &dev->dev;
- mips_cdmm_set_drvdata(dev, priv);
- atomic_set(&priv->xmit_total, 0);
- raw_spin_lock_init(&priv->lock);
- priv->reg = devm_ioremap(priv->dev, dev->res.start,
- resource_size(&dev->res));
- if (!priv->reg) {
- dev_err(priv->dev, "ioremap failed for resource %pR\n",
- &dev->res);
- return -ENOMEM;
- }
- cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
- tx_fifo = (cfg & REG_FDCFG_TXFIFOSIZE) >> REG_FDCFG_TXFIFOSIZE_SHIFT;
- /* Disable interrupts */
- cfg &= ~(REG_FDCFG_TXINTTHRES | REG_FDCFG_RXINTTHRES);
- cfg |= REG_FDCFG_TXINTTHRES_DISABLED;
- cfg |= REG_FDCFG_RXINTTHRES_DISABLED;
- mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
- /* Make each port's xmit FIFO big enough to fill FDC TX FIFO */
- priv->xmit_size = min(tx_fifo * 4, (unsigned int)SERIAL_XMIT_SIZE);
- driver = tty_alloc_driver(NUM_TTY_CHANNELS, TTY_DRIVER_REAL_RAW);
- if (IS_ERR(driver))
- return PTR_ERR(driver);
- priv->driver = driver;
- driver->driver_name = "ejtag_fdc";
- snprintf(priv->fdc_name, sizeof(priv->fdc_name), "ttyFDC%u", dev->cpu);
- snprintf(priv->driver_name, sizeof(priv->driver_name), "%sc",
- priv->fdc_name);
- driver->name = priv->driver_name;
- driver->major = 0; /* Auto-allocate */
- driver->minor_start = 0;
- driver->type = TTY_DRIVER_TYPE_SERIAL;
- driver->subtype = SERIAL_TYPE_NORMAL;
- driver->init_termios = tty_std_termios;
- driver->init_termios.c_cflag |= CLOCAL;
- driver->driver_state = priv;
- tty_set_operations(driver, &mips_ejtag_fdc_tty_ops);
- for (nport = 0; nport < NUM_TTY_CHANNELS; nport++) {
- dport = &priv->ports[nport];
- dport->driver = priv;
- tty_port_init(&dport->port);
- dport->port.ops = &mips_ejtag_fdc_tty_port_ops;
- raw_spin_lock_init(&dport->rx_lock);
- spin_lock_init(&dport->xmit_lock);
- /* The xmit buffer starts empty, i.e. completely written */
- init_completion(&dport->xmit_empty);
- complete(&dport->xmit_empty);
- }
- /* Set up the console */
- mips_ejtag_fdc_con.regs[dev->cpu] = priv->reg;
- if (dev->cpu == 0)
- mips_ejtag_fdc_con.tty_drv = driver;
- init_waitqueue_head(&priv->waitqueue);
- priv->thread = kthread_create(mips_ejtag_fdc_put, priv, priv->fdc_name);
- if (IS_ERR(priv->thread)) {
- ret = PTR_ERR(priv->thread);
- dev_err(priv->dev, "Couldn't create kthread (%d)\n", ret);
- goto err_destroy_ports;
- }
- /*
- * Bind the writer thread to the right CPU so it can't migrate.
- * The channels are per-CPU and we want all channel I/O to be on a
- * single predictable CPU.
- */
- kthread_bind(priv->thread, dev->cpu);
- wake_up_process(priv->thread);
- /* Look for an FDC IRQ */
- priv->irq = get_c0_fdc_int();
- /* Try requesting the IRQ */
- if (priv->irq >= 0) {
- /*
- * IRQF_SHARED, IRQF_COND_SUSPEND: The FDC IRQ may be shared with
- * other local interrupts such as the timer which sets
- * IRQF_TIMER (including IRQF_NO_SUSPEND).
- *
- * IRQF_NO_THREAD: The FDC IRQ isn't individually maskable so it
- * cannot be deferred and handled by a thread on RT kernels. For
- * this reason any spinlocks used from the ISR are raw.
- */
- ret = devm_request_irq(priv->dev, priv->irq, mips_ejtag_fdc_isr,
- IRQF_PERCPU | IRQF_SHARED |
- IRQF_NO_THREAD | IRQF_COND_SUSPEND,
- priv->fdc_name, priv);
- if (ret)
- priv->irq = -1;
- }
- if (priv->irq >= 0) {
- /* IRQ is usable, enable RX interrupt */
- raw_spin_lock_irq(&priv->lock);
- cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
- cfg &= ~REG_FDCFG_RXINTTHRES;
- cfg |= REG_FDCFG_RXINTTHRES_NOTEMPTY;
- mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
- raw_spin_unlock_irq(&priv->lock);
- } else {
- /* If we didn't get an usable IRQ, poll instead */
- timer_setup(&priv->poll_timer, mips_ejtag_fdc_tty_timer,
- TIMER_PINNED);
- priv->poll_timer.expires = jiffies + FDC_TTY_POLL;
- /*
- * Always attach the timer to the right CPU. The channels are
- * per-CPU so all polling should be from a single CPU.
- */
- add_timer_on(&priv->poll_timer, dev->cpu);
- dev_info(priv->dev, "No usable IRQ, polling enabled\n");
- }
- ret = tty_register_driver(driver);
- if (ret < 0) {
- dev_err(priv->dev, "Couldn't install tty driver (%d)\n", ret);
- goto err_stop_irq;
- }
- return 0;
- err_stop_irq:
- if (priv->irq >= 0) {
- raw_spin_lock_irq(&priv->lock);
- cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
- /* Disable interrupts */
- cfg &= ~(REG_FDCFG_TXINTTHRES | REG_FDCFG_RXINTTHRES);
- cfg |= REG_FDCFG_TXINTTHRES_DISABLED;
- cfg |= REG_FDCFG_RXINTTHRES_DISABLED;
- mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
- raw_spin_unlock_irq(&priv->lock);
- } else {
- priv->removing = true;
- del_timer_sync(&priv->poll_timer);
- }
- kthread_stop(priv->thread);
- err_destroy_ports:
- if (dev->cpu == 0)
- mips_ejtag_fdc_con.tty_drv = NULL;
- for (nport = 0; nport < NUM_TTY_CHANNELS; nport++) {
- dport = &priv->ports[nport];
- tty_port_destroy(&dport->port);
- }
- put_tty_driver(priv->driver);
- return ret;
- }
- static int mips_ejtag_fdc_tty_cpu_down(struct mips_cdmm_device *dev)
- {
- struct mips_ejtag_fdc_tty *priv = mips_cdmm_get_drvdata(dev);
- unsigned int cfg;
- if (priv->irq >= 0) {
- raw_spin_lock_irq(&priv->lock);
- cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
- /* Disable interrupts */
- cfg &= ~(REG_FDCFG_TXINTTHRES | REG_FDCFG_RXINTTHRES);
- cfg |= REG_FDCFG_TXINTTHRES_DISABLED;
- cfg |= REG_FDCFG_RXINTTHRES_DISABLED;
- mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
- raw_spin_unlock_irq(&priv->lock);
- } else {
- priv->removing = true;
- del_timer_sync(&priv->poll_timer);
- }
- kthread_stop(priv->thread);
- return 0;
- }
- static int mips_ejtag_fdc_tty_cpu_up(struct mips_cdmm_device *dev)
- {
- struct mips_ejtag_fdc_tty *priv = mips_cdmm_get_drvdata(dev);
- unsigned int cfg;
- int ret = 0;
- if (priv->irq >= 0) {
- /*
- * IRQ is usable, enable RX interrupt
- * This must be before kthread is restarted, as kthread may
- * enable TX interrupt.
- */
- raw_spin_lock_irq(&priv->lock);
- cfg = mips_ejtag_fdc_read(priv, REG_FDCFG);
- cfg &= ~(REG_FDCFG_TXINTTHRES | REG_FDCFG_RXINTTHRES);
- cfg |= REG_FDCFG_TXINTTHRES_DISABLED;
- cfg |= REG_FDCFG_RXINTTHRES_NOTEMPTY;
- mips_ejtag_fdc_write(priv, REG_FDCFG, cfg);
- raw_spin_unlock_irq(&priv->lock);
- } else {
- /* Restart poll timer */
- priv->removing = false;
- add_timer_on(&priv->poll_timer, dev->cpu);
- }
- /* Restart the kthread */
- priv->thread = kthread_create(mips_ejtag_fdc_put, priv, priv->fdc_name);
- if (IS_ERR(priv->thread)) {
- ret = PTR_ERR(priv->thread);
- dev_err(priv->dev, "Couldn't re-create kthread (%d)\n", ret);
- goto out;
- }
- /* Bind it back to the right CPU and set it off */
- kthread_bind(priv->thread, dev->cpu);
- wake_up_process(priv->thread);
- out:
- return ret;
- }
- static const struct mips_cdmm_device_id mips_ejtag_fdc_tty_ids[] = {
- { .type = 0xfd },
- { }
- };
- static struct mips_cdmm_driver mips_ejtag_fdc_tty_driver = {
- .drv = {
- .name = "mips_ejtag_fdc",
- },
- .probe = mips_ejtag_fdc_tty_probe,
- .cpu_down = mips_ejtag_fdc_tty_cpu_down,
- .cpu_up = mips_ejtag_fdc_tty_cpu_up,
- .id_table = mips_ejtag_fdc_tty_ids,
- };
- builtin_mips_cdmm_driver(mips_ejtag_fdc_tty_driver);
- static int __init mips_ejtag_fdc_init_console(void)
- {
- return mips_ejtag_fdc_console_init(&mips_ejtag_fdc_con);
- }
- console_initcall(mips_ejtag_fdc_init_console);
- #ifdef CONFIG_MIPS_EJTAG_FDC_EARLYCON
- static struct mips_ejtag_fdc_console mips_ejtag_fdc_earlycon = {
- .cons = {
- .name = "early_fdc",
- .write = mips_ejtag_fdc_console_write,
- .flags = CON_PRINTBUFFER | CON_BOOT,
- .index = CONSOLE_CHANNEL,
- },
- .lock = __RAW_SPIN_LOCK_UNLOCKED(mips_ejtag_fdc_earlycon.lock),
- };
- int __init setup_early_fdc_console(void)
- {
- return mips_ejtag_fdc_console_init(&mips_ejtag_fdc_earlycon);
- }
- #endif
- #ifdef CONFIG_MIPS_EJTAG_FDC_KGDB
- /* read buffer to allow decompaction */
- static unsigned int kgdbfdc_rbuflen;
- static unsigned int kgdbfdc_rpos;
- static char kgdbfdc_rbuf[4];
- /* write buffer to allow compaction */
- static unsigned int kgdbfdc_wbuflen;
- static char kgdbfdc_wbuf[4];
- static void __iomem *kgdbfdc_setup(void)
- {
- void __iomem *regs;
- unsigned int cpu;
- /* Find address, piggy backing off console percpu regs */
- cpu = smp_processor_id();
- regs = mips_ejtag_fdc_con.regs[cpu];
- /* First console output on this CPU? */
- if (!regs) {
- regs = mips_cdmm_early_probe(0xfd);
- mips_ejtag_fdc_con.regs[cpu] = regs;
- }
- /* Already tried and failed to find FDC on this CPU? */
- if (IS_ERR(regs))
- return regs;
- return regs;
- }
- /* read a character from the read buffer, filling from FDC RX FIFO */
- static int kgdbfdc_read_char(void)
- {
- unsigned int stat, channel, data;
- void __iomem *regs;
- /* No more data, try and read another FDC word from RX FIFO */
- if (kgdbfdc_rpos >= kgdbfdc_rbuflen) {
- kgdbfdc_rpos = 0;
- kgdbfdc_rbuflen = 0;
- regs = kgdbfdc_setup();
- if (IS_ERR(regs))
- return NO_POLL_CHAR;
- /* Read next word from KGDB channel */
- do {
- stat = __raw_readl(regs + REG_FDSTAT);
- /* No data waiting? */
- if (stat & REG_FDSTAT_RXE)
- return NO_POLL_CHAR;
- /* Read next word */
- channel = (stat & REG_FDSTAT_RXCHAN) >>
- REG_FDSTAT_RXCHAN_SHIFT;
- data = __raw_readl(regs + REG_FDRX);
- } while (channel != CONFIG_MIPS_EJTAG_FDC_KGDB_CHAN);
- /* Decode into rbuf */
- kgdbfdc_rbuflen = mips_ejtag_fdc_decode(data, kgdbfdc_rbuf);
- }
- pr_devel("kgdbfdc r %c\n", kgdbfdc_rbuf[kgdbfdc_rpos]);
- return kgdbfdc_rbuf[kgdbfdc_rpos++];
- }
- /* push an FDC word from write buffer to TX FIFO */
- static void kgdbfdc_push_one(void)
- {
- const char *bufs[1] = { kgdbfdc_wbuf };
- struct fdc_word word;
- void __iomem *regs;
- unsigned int i;
- /* Construct a word from any data in buffer */
- word = mips_ejtag_fdc_encode(bufs, &kgdbfdc_wbuflen, 1);
- /* Relocate any remaining data to beginnning of buffer */
- kgdbfdc_wbuflen -= word.bytes;
- for (i = 0; i < kgdbfdc_wbuflen; ++i)
- kgdbfdc_wbuf[i] = kgdbfdc_wbuf[i + word.bytes];
- regs = kgdbfdc_setup();
- if (IS_ERR(regs))
- return;
- /* Busy wait until there's space in fifo */
- while (__raw_readl(regs + REG_FDSTAT) & REG_FDSTAT_TXF)
- ;
- __raw_writel(word.word,
- regs + REG_FDTX(CONFIG_MIPS_EJTAG_FDC_KGDB_CHAN));
- }
- /* flush the whole write buffer to the TX FIFO */
- static void kgdbfdc_flush(void)
- {
- while (kgdbfdc_wbuflen)
- kgdbfdc_push_one();
- }
- /* write a character into the write buffer, writing out if full */
- static void kgdbfdc_write_char(u8 chr)
- {
- pr_devel("kgdbfdc w %c\n", chr);
- kgdbfdc_wbuf[kgdbfdc_wbuflen++] = chr;
- if (kgdbfdc_wbuflen >= sizeof(kgdbfdc_wbuf))
- kgdbfdc_push_one();
- }
- static struct kgdb_io kgdbfdc_io_ops = {
- .name = "kgdbfdc",
- .read_char = kgdbfdc_read_char,
- .write_char = kgdbfdc_write_char,
- .flush = kgdbfdc_flush,
- };
- static int __init kgdbfdc_init(void)
- {
- kgdb_register_io_module(&kgdbfdc_io_ops);
- return 0;
- }
- early_initcall(kgdbfdc_init);
- #endif
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