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@@ -0,0 +1,280 @@
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+// SPDX-License-Identifier: GPL-2.0+
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+/*
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+ * Copyright (c) 2018 Arm Ltd.
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+ * Author: Liviu Dudau <liviu.dudau@foss.arm.com>
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+ *
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+ */
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+
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+#include <common.h>
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+#include <dm.h>
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+#include <errno.h>
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+#include <i2c.h>
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+#include <asm/io.h>
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+#include <clk.h>
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+#include <linux/io.h>
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+
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+#define I2C_CONTROL_REG 0x00
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+#define I2C_SET_REG 0x00
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+#define I2C_CLEAR_REG 0x04
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+
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+#define SCL BIT(0)
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+#define SDA BIT(1)
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+
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+struct versatile_i2c_priv {
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+ phys_addr_t base;
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+ u32 delay;
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+};
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+
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+static inline void versatile_sda_set(struct versatile_i2c_priv *priv, u8 state)
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+{
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+ writel(SDA, priv->base + (state ? I2C_SET_REG : I2C_CLEAR_REG));
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+ udelay(priv->delay);
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+}
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+
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+static inline int versatile_sda_get(struct versatile_i2c_priv *priv)
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+{
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+ int v = !!(readl(priv->base + I2C_CONTROL_REG) & SDA);
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+
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+ udelay(priv->delay);
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+ return v;
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+}
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+
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+static inline void versatile_scl_set(struct versatile_i2c_priv *priv, u8 state)
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+{
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+ writel(SCL, priv->base + (state ? I2C_SET_REG : I2C_CLEAR_REG));
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+ udelay(priv->delay);
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+}
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+
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+static inline int versatile_scl_get(struct versatile_i2c_priv *priv)
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+{
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+ int v = !!(readl(priv->base + I2C_CONTROL_REG) & SCL);
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+
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+ udelay(priv->delay);
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+ return v;
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+}
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+
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+/* start: SDA goes from high to low while SCL is high */
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+static void versatile_i2c_start(struct versatile_i2c_priv *priv)
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+{
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+ udelay(priv->delay);
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+ versatile_sda_set(priv, 1);
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+ versatile_scl_set(priv, 1);
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+ versatile_sda_set(priv, 0);
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+}
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+
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+/* stop: SDA goes from low to high while SCL is high */
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+static void versatile_i2c_stop(struct versatile_i2c_priv *priv)
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+{
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+ versatile_scl_set(priv, 0);
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+ versatile_sda_set(priv, 0);
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+ versatile_scl_set(priv, 1);
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+ versatile_sda_set(priv, 1);
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+}
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+
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+/* read a bit from the SDA line (data or ACK/NACK) */
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+static u8 versatile_i2c_read_bit(struct versatile_i2c_priv *priv)
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+{
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+ versatile_scl_set(priv, 0);
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+ versatile_sda_set(priv, 1);
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+ versatile_scl_set(priv, 1);
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+ udelay(priv->delay);
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+ return (u8)versatile_sda_get(priv);
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+}
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+
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+/* write a bit on the SDA line */
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+static void versatile_i2c_write_bit(struct versatile_i2c_priv *priv, u8 bit)
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+{
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+ versatile_scl_set(priv, 0);
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+ versatile_sda_set(priv, bit);
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+ versatile_scl_set(priv, 1);
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+ udelay(priv->delay);
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+}
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+
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+/* send a reset sequence of 9 clocks with SDA high */
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+static void versatile_i2c_reset_bus(struct versatile_i2c_priv *priv)
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+{
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+ int i;
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+
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+ for (i = 0; i < 9; i++)
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+ versatile_i2c_write_bit(priv, 1);
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+
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+ versatile_i2c_stop(priv);
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+}
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+
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+/* write byte without start/stop sequence */
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+static int versatile_i2c_write_byte(struct versatile_i2c_priv *priv, u8 byte)
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+{
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+ u8 nak, i;
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+
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+ for (i = 0; i < 8; i++) {
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+ versatile_i2c_write_bit(priv, byte & 0x80);
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+ byte <<= 1;
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+ }
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+
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+ /* read ACK */
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+ nak = versatile_i2c_read_bit(priv);
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+ versatile_scl_set(priv, 0);
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+
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+ return nak; /* not a nack is an ack */
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+}
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+
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+static int versatile_i2c_read_byte(struct versatile_i2c_priv *priv,
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+ u8 *byte, u8 ack)
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+{
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+ u8 i;
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+
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+ *byte = 0;
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+ for (i = 0; i < 8; i++) {
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+ *byte <<= 1;
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+ *byte |= versatile_i2c_read_bit(priv);
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+ }
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+ /* write the nack */
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+ versatile_i2c_write_bit(priv, ack);
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+
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+ return 0;
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+}
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+
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+static int versatile_i2c_send_slave_addr(struct versatile_i2c_priv *priv,
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+ struct i2c_msg *msg)
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+{
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+ u8 addr;
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+ int ret;
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+
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+ if (msg->flags & I2C_M_TEN) {
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+ /* 10-bit address, send extended address code first */
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+ addr = 0xf0 | ((msg->addr >> 7) & 0x06);
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+ ret = versatile_i2c_write_byte(priv, addr);
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+ if (ret) {
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+ versatile_i2c_stop(priv);
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+ return -EIO;
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+ }
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+
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+ /* remaining bits */
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+ ret = versatile_i2c_write_byte(priv, msg->addr & 0xff);
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+ if (ret) {
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+ versatile_i2c_stop(priv);
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+ return -EIO;
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+ }
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+ /* reads need to resend the addr */
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+ if (msg->flags & I2C_M_RD) {
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+ versatile_i2c_start(priv);
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+ addr |= 1;
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+ ret = versatile_i2c_write_byte(priv, addr);
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+ if (ret) {
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+ versatile_i2c_stop(priv);
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+ return -EIO;
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+ }
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+ }
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+ } else {
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+ /* normal 7-bit address */
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+ addr = msg->addr << 1;
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+ if (msg->flags & I2C_M_RD)
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+ addr |= 1;
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+ ret = versatile_i2c_write_byte(priv, addr);
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+ if (ret) {
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+ versatile_i2c_stop(priv);
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+ return -EIO;
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+ }
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+ }
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+
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+ return 0;
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+}
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+
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+static int versatile_i2c_message_xfer(struct versatile_i2c_priv *priv,
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+ struct i2c_msg *msg)
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+{
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+ int i, ret;
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+ u8 ack;
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+
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+ versatile_i2c_start(priv);
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+ if (versatile_i2c_send_slave_addr(priv, msg))
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+ return -EIO;
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+
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+ for (i = 0; i < msg->len; i++) {
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+ if (msg->flags & I2C_M_RD) {
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+ ack = (msg->len - i - 1) == 0 ? 1 : 0;
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+ ret = versatile_i2c_read_byte(priv, &msg->buf[i], ack);
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+ } else {
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+ ret = versatile_i2c_write_byte(priv, msg->buf[i]);
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+ }
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+
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+ if (ret)
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+ break;
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+ }
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+
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+ versatile_i2c_stop(priv);
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+
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+ return ret;
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+}
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+
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+static int versatile_i2c_xfer(struct udevice *bus,
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+ struct i2c_msg *msg, int nmsgs)
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+{
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+ struct versatile_i2c_priv *priv = dev_get_priv(bus);
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+ int ret;
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+
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+ for ( ; nmsgs > 0; nmsgs--, msg++) {
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+ ret = versatile_i2c_message_xfer(priv, msg);
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+ if (ret)
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+ return -EREMOTEIO;
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+ }
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+
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+ return 0;
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+}
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+
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+static int versatile_i2c_chip_probe(struct udevice *bus,
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+ uint chip, uint chip_flags)
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+{
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+ /* probe the presence of a slave by writing a 0-size message */
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+ struct i2c_msg msg = { .addr = chip, .flags = chip_flags,
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+ .len = 0, .buf = NULL };
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+ struct versatile_i2c_priv *priv = dev_get_priv(bus);
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+
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+ return versatile_i2c_message_xfer(priv, &msg);
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+}
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+
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+static int versatile_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
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+{
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+ struct versatile_i2c_priv *priv = dev_get_priv(bus);
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+
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+ priv->delay = 1000000 / (speed << 2);
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+
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+ versatile_i2c_reset_bus(priv);
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+
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+ return 0;
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+}
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+
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+static int versatile_i2c_probe(struct udevice *dev)
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+{
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+ struct versatile_i2c_priv *priv = dev_get_priv(dev);
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+
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+ priv->base = (phys_addr_t)dev_read_addr(dev);
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+ priv->delay = 25; /* 25us * 4 = 100kHz */
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+ /*
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+ * U-Boot still doesn't assign automatically
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+ * sequence numbers to devices
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+ */
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+ dev->req_seq = 1;
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+
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+ return 0;
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+}
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+
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+static const struct dm_i2c_ops versatile_i2c_ops = {
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+ .xfer = versatile_i2c_xfer,
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+ .probe_chip = versatile_i2c_chip_probe,
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+ .set_bus_speed = versatile_i2c_set_bus_speed,
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+};
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+
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+static const struct udevice_id versatile_i2c_of_match[] = {
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+ { .compatible = "arm,versatile-i2c" },
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+ { }
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+};
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+
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+U_BOOT_DRIVER(versatile_i2c) = {
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+ .name = "i2c-bus-versatile",
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+ .id = UCLASS_I2C,
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+ .of_match = versatile_i2c_of_match,
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+ .probe = versatile_i2c_probe,
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+ .priv_auto_alloc_size = sizeof(struct versatile_i2c_priv),
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+ .ops = &versatile_i2c_ops,
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+};
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