u-boot/drivers/i2c/ast_i2c.c
Eddie James 6ac25538d8 i2c: ast_i2c: Remove SCL direct drive mode
SCL direct drive mode prevents communication with devices that
do clock stretching, so disable. The Linux driver doesn't use
this mode, and the engine can handle clock stretching.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: ryan_chen <ryan_chen@aspeedtech.com>
2022-07-19 13:46:28 +02:00

366 lines
8.1 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2012-2020 ASPEED Technology Inc.
* Copyright 2016 IBM Corporation
* Copyright 2017 Google, Inc.
*/
#include <common.h>
#include <clk.h>
#include <dm.h>
#include <errno.h>
#include <fdtdec.h>
#include <i2c.h>
#include <log.h>
#include <asm/io.h>
#include <asm/arch/scu_ast2500.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <reset.h>
#include "ast_i2c.h"
#define I2C_TIMEOUT_US 100000
#define I2C_SLEEP_STEP_US 20
#define HIGHSPEED_TTIMEOUT 3
/*
* Device private data
*/
struct ast_i2c_priv {
/* This device's clock */
struct clk clk;
/* Device registers */
struct ast_i2c_regs *regs;
/* I2C speed in Hz */
int speed;
};
/*
* Given desired divider ratio, return the value that needs to be set
* in Clock and AC Timing Control register
*/
static u32 get_clk_reg_val(ulong divider_ratio)
{
ulong inc = 0, div;
ulong scl_low, scl_high, data;
for (div = 0; divider_ratio >= 16; div++) {
inc |= (divider_ratio & 1);
divider_ratio >>= 1;
}
divider_ratio += inc;
scl_low = (divider_ratio >> 1) - 1;
scl_high = divider_ratio - scl_low - 2;
data = I2CD_CACTC_BASE
| (scl_high << I2CD_TCKHIGH_SHIFT)
| (scl_low << I2CD_TCKLOW_SHIFT)
| (div << I2CD_BASE_DIV_SHIFT);
return data;
}
static void ast_i2c_clear_interrupts(struct udevice *dev)
{
struct ast_i2c_priv *priv = dev_get_priv(dev);
writel(~0, &priv->regs->isr);
}
static void ast_i2c_init_bus(struct udevice *dev)
{
struct ast_i2c_priv *priv = dev_get_priv(dev);
/* Reset device */
writel(0, &priv->regs->fcr);
/* Enable Master Mode. Assuming single-master */
writel(I2CD_MASTER_EN
| I2CD_M_SDA_LOCK_EN
| I2CD_MULTI_MASTER_DIS,
&priv->regs->fcr);
/* Enable Interrupts */
writel(I2CD_INTR_TX_ACK
| I2CD_INTR_TX_NAK
| I2CD_INTR_RX_DONE
| I2CD_INTR_BUS_RECOVER_DONE
| I2CD_INTR_NORMAL_STOP
| I2CD_INTR_ABNORMAL, &priv->regs->icr);
}
static int ast_i2c_of_to_plat(struct udevice *dev)
{
struct ast_i2c_priv *priv = dev_get_priv(dev);
int ret;
priv->regs = dev_read_addr_ptr(dev);
if (!priv->regs)
return -EINVAL;
ret = clk_get_by_index(dev, 0, &priv->clk);
if (ret < 0) {
debug("%s: Can't get clock for %s: %d\n", __func__, dev->name,
ret);
return ret;
}
return 0;
}
static int ast_i2c_probe(struct udevice *dev)
{
struct reset_ctl reset_ctl;
int rc;
debug("Enabling I2C%u\n", dev_seq(dev));
/*
* Get all I2C devices out of Reset.
*
* Only needs to be done once so test before performing reset.
*/
rc = reset_get_by_index(dev, 0, &reset_ctl);
if (rc) {
printf("%s: Failed to get reset signal\n", __func__);
return rc;
}
if (reset_status(&reset_ctl) > 0) {
reset_assert(&reset_ctl);
reset_deassert(&reset_ctl);
}
ast_i2c_init_bus(dev);
return 0;
}
static int ast_i2c_wait_isr(struct udevice *dev, u32 flag)
{
struct ast_i2c_priv *priv = dev_get_priv(dev);
int timeout = I2C_TIMEOUT_US;
while (!(readl(&priv->regs->isr) & flag) && timeout > 0) {
udelay(I2C_SLEEP_STEP_US);
timeout -= I2C_SLEEP_STEP_US;
}
ast_i2c_clear_interrupts(dev);
if (timeout <= 0)
return -ETIMEDOUT;
return 0;
}
static int ast_i2c_send_stop(struct udevice *dev)
{
struct ast_i2c_priv *priv = dev_get_priv(dev);
writel(I2CD_M_STOP_CMD, &priv->regs->csr);
return ast_i2c_wait_isr(dev, I2CD_INTR_NORMAL_STOP);
}
static int ast_i2c_wait_tx(struct udevice *dev)
{
struct ast_i2c_priv *priv = dev_get_priv(dev);
int timeout = I2C_TIMEOUT_US;
u32 flag = I2CD_INTR_TX_ACK | I2CD_INTR_TX_NAK;
u32 status = readl(&priv->regs->isr) & flag;
int ret = 0;
while (!status && timeout > 0) {
status = readl(&priv->regs->isr) & flag;
udelay(I2C_SLEEP_STEP_US);
timeout -= I2C_SLEEP_STEP_US;
}
if (status == I2CD_INTR_TX_NAK)
ret = -EREMOTEIO;
if (timeout <= 0)
ret = -ETIMEDOUT;
ast_i2c_clear_interrupts(dev);
return ret;
}
static int ast_i2c_start_txn(struct udevice *dev, uint devaddr)
{
struct ast_i2c_priv *priv = dev_get_priv(dev);
/* Start and Send Device Address */
writel(devaddr, &priv->regs->trbbr);
writel(I2CD_M_START_CMD | I2CD_M_TX_CMD, &priv->regs->csr);
return ast_i2c_wait_tx(dev);
}
static int ast_i2c_read_data(struct udevice *dev, u8 chip_addr, u8 *buffer,
size_t len, bool send_stop)
{
struct ast_i2c_priv *priv = dev_get_priv(dev);
u32 i2c_cmd = I2CD_M_RX_CMD;
int ret;
ret = ast_i2c_start_txn(dev, (chip_addr << 1) | I2C_M_RD);
if (ret < 0)
return ret;
for (; len > 0; len--, buffer++) {
if (len == 1)
i2c_cmd |= I2CD_M_S_RX_CMD_LAST;
writel(i2c_cmd, &priv->regs->csr);
ret = ast_i2c_wait_isr(dev, I2CD_INTR_RX_DONE);
if (ret < 0)
return ret;
*buffer = (readl(&priv->regs->trbbr) & I2CD_RX_DATA_MASK)
>> I2CD_RX_DATA_SHIFT;
}
ast_i2c_clear_interrupts(dev);
if (send_stop)
return ast_i2c_send_stop(dev);
return 0;
}
static int ast_i2c_write_data(struct udevice *dev, u8 chip_addr, u8
*buffer, size_t len, bool send_stop)
{
struct ast_i2c_priv *priv = dev_get_priv(dev);
int ret;
ret = ast_i2c_start_txn(dev, (chip_addr << 1));
if (ret < 0)
return ret;
for (; len > 0; len--, buffer++) {
writel(*buffer, &priv->regs->trbbr);
writel(I2CD_M_TX_CMD, &priv->regs->csr);
ret = ast_i2c_wait_tx(dev);
if (ret < 0)
return ret;
}
if (send_stop)
return ast_i2c_send_stop(dev);
return 0;
}
static int ast_i2c_deblock(struct udevice *dev)
{
struct ast_i2c_priv *priv = dev_get_priv(dev);
struct ast_i2c_regs *regs = priv->regs;
u32 csr = readl(&regs->csr);
bool sda_high = csr & I2CD_SDA_LINE_STS;
bool scl_high = csr & I2CD_SCL_LINE_STS;
int ret = 0;
if (sda_high && scl_high) {
/* Bus is idle, no deblocking needed. */
return 0;
} else if (sda_high) {
/* Send stop command */
debug("Unterminated TXN in (%x), sending stop\n", csr);
ret = ast_i2c_send_stop(dev);
} else if (scl_high) {
/* Possibly stuck slave */
debug("Bus stuck (%x), attempting recovery\n", csr);
writel(I2CD_BUS_RECOVER_CMD, &regs->csr);
ret = ast_i2c_wait_isr(dev, I2CD_INTR_BUS_RECOVER_DONE);
} else {
/* Just try to reinit the device. */
ast_i2c_init_bus(dev);
}
return ret;
}
static int ast_i2c_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
{
int ret;
ret = ast_i2c_deblock(dev);
if (ret < 0)
return ret;
debug("i2c_xfer: %d messages\n", nmsgs);
for (; nmsgs > 0; nmsgs--, msg++) {
if (msg->flags & I2C_M_RD) {
debug("i2c_read: chip=0x%x, len=0x%x, flags=0x%x\n",
msg->addr, msg->len, msg->flags);
ret = ast_i2c_read_data(dev, msg->addr, msg->buf,
msg->len, (nmsgs == 1));
} else {
debug("i2c_write: chip=0x%x, len=0x%x, flags=0x%x\n",
msg->addr, msg->len, msg->flags);
ret = ast_i2c_write_data(dev, msg->addr, msg->buf,
msg->len, (nmsgs == 1));
}
if (ret) {
debug("%s: error (%d)\n", __func__, ret);
return -EREMOTEIO;
}
}
return 0;
}
static int ast_i2c_set_speed(struct udevice *dev, unsigned int speed)
{
struct ast_i2c_priv *priv = dev_get_priv(dev);
struct ast_i2c_regs *regs = priv->regs;
ulong i2c_rate, divider;
debug("Setting speed for I2C%d to <%u>\n", dev_seq(dev), speed);
if (!speed) {
debug("No valid speed specified\n");
return -EINVAL;
}
i2c_rate = clk_get_rate(&priv->clk);
divider = i2c_rate / speed;
priv->speed = speed;
if (speed > I2C_SPEED_FAST_RATE) {
debug("Enable High Speed\n");
setbits_le32(&regs->fcr, I2CD_M_HIGH_SPEED_EN
| I2CD_M_SDA_DRIVE_1T_EN
| I2CD_SDA_DRIVE_1T_EN);
writel(HIGHSPEED_TTIMEOUT, &regs->cactcr2);
} else {
debug("Enabling Normal Speed\n");
writel(I2CD_NO_TIMEOUT_CTRL, &regs->cactcr2);
}
writel(get_clk_reg_val(divider), &regs->cactcr1);
ast_i2c_clear_interrupts(dev);
return 0;
}
static const struct dm_i2c_ops ast_i2c_ops = {
.xfer = ast_i2c_xfer,
.set_bus_speed = ast_i2c_set_speed,
.deblock = ast_i2c_deblock,
};
static const struct udevice_id ast_i2c_ids[] = {
{ .compatible = "aspeed,ast2400-i2c-bus" },
{ .compatible = "aspeed,ast2500-i2c-bus" },
{ .compatible = "aspeed,ast2600-i2c-bus" },
{ },
};
U_BOOT_DRIVER(ast_i2c) = {
.name = "ast_i2c",
.id = UCLASS_I2C,
.of_match = ast_i2c_ids,
.probe = ast_i2c_probe,
.of_to_plat = ast_i2c_of_to_plat,
.priv_auto = sizeof(struct ast_i2c_priv),
.ops = &ast_i2c_ops,
};