281 lines
6.0 KiB
C
281 lines
6.0 KiB
C
// 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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#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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#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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#define SCL BIT(0)
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#define SDA BIT(1)
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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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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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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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udelay(priv->delay);
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return v;
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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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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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udelay(priv->delay);
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return v;
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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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/* 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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/* 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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/* 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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/* 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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for (i = 0; i < 9; i++)
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versatile_i2c_write_bit(priv, 1);
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versatile_i2c_stop(priv);
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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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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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/* 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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return nak; /* not a nack is an ack */
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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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*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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return 0;
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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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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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/* 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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return 0;
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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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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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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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if (ret)
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break;
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}
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versatile_i2c_stop(priv);
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return ret;
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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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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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return 0;
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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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return versatile_i2c_message_xfer(priv, &msg);
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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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priv->delay = 1000000 / (speed << 2);
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versatile_i2c_reset_bus(priv);
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return 0;
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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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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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return 0;
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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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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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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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