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- // SPDX-License-Identifier: GPL-2.0
- /*
- * (C) 2018 NXP
- * (C) 2020 EPAM Systems Inc.
- */
- #include <common.h>
- #include <cpu_func.h>
- #include <dm.h>
- #include <serial.h>
- #include <watchdog.h>
- #include <asm/global_data.h>
- #include <linux/bug.h>
- #include <xen/hvm.h>
- #include <xen/events.h>
- #include <xen/interface/sched.h>
- #include <xen/interface/hvm/hvm_op.h>
- #include <xen/interface/hvm/params.h>
- #include <xen/interface/io/console.h>
- #include <xen/interface/io/ring.h>
- DECLARE_GLOBAL_DATA_PTR;
- u32 console_evtchn;
- /*
- * struct xen_uart_priv - Structure representing a Xen UART info
- * @intf: Console I/O interface for Xen guest OSes
- * @evtchn: Console event channel
- */
- struct xen_uart_priv {
- struct xencons_interface *intf;
- u32 evtchn;
- };
- int xen_serial_setbrg(struct udevice *dev, int baudrate)
- {
- return 0;
- }
- static int xen_serial_probe(struct udevice *dev)
- {
- struct xen_uart_priv *priv = dev_get_priv(dev);
- u64 val = 0;
- unsigned long gfn;
- int ret;
- ret = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &val);
- if (ret < 0 || val == 0)
- return ret;
- priv->evtchn = val;
- console_evtchn = val;
- ret = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &val);
- if (ret < 0)
- return ret;
- if (!val)
- return -EINVAL;
- gfn = val;
- priv->intf = (struct xencons_interface *)(gfn << XEN_PAGE_SHIFT);
- return 0;
- }
- static int xen_serial_pending(struct udevice *dev, bool input)
- {
- struct xen_uart_priv *priv = dev_get_priv(dev);
- struct xencons_interface *intf = priv->intf;
- if (!input || intf->in_cons == intf->in_prod)
- return 0;
- return 1;
- }
- static int xen_serial_getc(struct udevice *dev)
- {
- struct xen_uart_priv *priv = dev_get_priv(dev);
- struct xencons_interface *intf = priv->intf;
- XENCONS_RING_IDX cons;
- char c;
- while (intf->in_cons == intf->in_prod)
- mb(); /* wait */
- cons = intf->in_cons;
- mb(); /* get pointers before reading ring */
- c = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
- mb(); /* read ring before consuming */
- intf->in_cons = cons;
- notify_remote_via_evtchn(priv->evtchn);
- return c;
- }
- static int __write_console(struct udevice *dev, const char *data, int len)
- {
- struct xen_uart_priv *priv = dev_get_priv(dev);
- struct xencons_interface *intf = priv->intf;
- XENCONS_RING_IDX cons, prod;
- int sent = 0;
- cons = intf->out_cons;
- prod = intf->out_prod;
- mb(); /* Update pointer */
- WARN_ON((prod - cons) > sizeof(intf->out));
- while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
- intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
- mb(); /* Update data before pointer */
- intf->out_prod = prod;
- if (sent)
- notify_remote_via_evtchn(priv->evtchn);
- return sent;
- }
- static int write_console(struct udevice *dev, const char *data, int len)
- {
- /*
- * Make sure the whole buffer is emitted, polling if
- * necessary. We don't ever want to rely on the hvc daemon
- * because the most interesting console output is when the
- * kernel is crippled.
- */
- while (len) {
- int sent = __write_console(dev, data, len);
- data += sent;
- len -= sent;
- if (unlikely(len))
- HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
- }
- return 0;
- }
- static int xen_serial_putc(struct udevice *dev, const char ch)
- {
- write_console(dev, &ch, 1);
- return 0;
- }
- static const struct dm_serial_ops xen_serial_ops = {
- .putc = xen_serial_putc,
- .getc = xen_serial_getc,
- .pending = xen_serial_pending,
- };
- #if CONFIG_IS_ENABLED(OF_CONTROL)
- static const struct udevice_id xen_serial_ids[] = {
- { .compatible = "xen,xen" },
- { }
- };
- #endif
- U_BOOT_DRIVER(serial_xen) = {
- .name = "serial_xen",
- .id = UCLASS_SERIAL,
- #if CONFIG_IS_ENABLED(OF_CONTROL)
- .of_match = xen_serial_ids,
- #endif
- .priv_auto = sizeof(struct xen_uart_priv),
- .probe = xen_serial_probe,
- .ops = &xen_serial_ops,
- #if !CONFIG_IS_ENABLED(OF_CONTROL)
- .flags = DM_FLAG_PRE_RELOC,
- #endif
- };
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