- 根目录:
- drivers
- i2c
- busses
- i2c-uniphier.c
/*
* Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/clk.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#define UNIPHIER_I2C_DTRM 0x00 /* TX register */
#define UNIPHIER_I2C_DTRM_IRQEN BIT(11) /* enable interrupt */
#define UNIPHIER_I2C_DTRM_STA BIT(10) /* start condition */
#define UNIPHIER_I2C_DTRM_STO BIT(9) /* stop condition */
#define UNIPHIER_I2C_DTRM_NACK BIT(8) /* do not return ACK */
#define UNIPHIER_I2C_DTRM_RD BIT(0) /* read transaction */
#define UNIPHIER_I2C_DREC 0x04 /* RX register */
#define UNIPHIER_I2C_DREC_MST BIT(14) /* 1 = master, 0 = slave */
#define UNIPHIER_I2C_DREC_TX BIT(13) /* 1 = transmit, 0 = receive */
#define UNIPHIER_I2C_DREC_STS BIT(12) /* stop condition detected */
#define UNIPHIER_I2C_DREC_LRB BIT(11) /* no ACK */
#define UNIPHIER_I2C_DREC_LAB BIT(9) /* arbitration lost */
#define UNIPHIER_I2C_DREC_BBN BIT(8) /* bus not busy */
#define UNIPHIER_I2C_MYAD 0x08 /* slave address */
#define UNIPHIER_I2C_CLK 0x0c /* clock frequency control */
#define UNIPHIER_I2C_BRST 0x10 /* bus reset */
#define UNIPHIER_I2C_BRST_FOEN BIT(1) /* normal operation */
#define UNIPHIER_I2C_BRST_RSCL BIT(0) /* release SCL */
#define UNIPHIER_I2C_HOLD 0x14 /* hold time control */
#define UNIPHIER_I2C_BSTS 0x18 /* bus status monitor */
#define UNIPHIER_I2C_BSTS_SDA BIT(1) /* readback of SDA line */
#define UNIPHIER_I2C_BSTS_SCL BIT(0) /* readback of SCL line */
#define UNIPHIER_I2C_NOISE 0x1c /* noise filter control */
#define UNIPHIER_I2C_SETUP 0x20 /* setup time control */
#define UNIPHIER_I2C_DEFAULT_SPEED 100000
#define UNIPHIER_I2C_MAX_SPEED 400000
struct uniphier_i2c_priv {
struct completion comp;
struct i2c_adapter adap;
void __iomem *membase;
struct clk *clk;
unsigned int busy_cnt;
};
static irqreturn_t uniphier_i2c_interrupt(int irq, void *dev_id)
{
struct uniphier_i2c_priv *priv = dev_id;
/*
* This hardware uses edge triggered interrupt. Do not touch the
* hardware registers in this handler to make sure to catch the next
* interrupt edge. Just send a complete signal and return.
*/
complete(&priv->comp);
return IRQ_HANDLED;
}
static int uniphier_i2c_xfer_byte(struct i2c_adapter *adap, u32 txdata,
u32 *rxdatap)
{
struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
unsigned long time_left;
u32 rxdata;
reinit_completion(&priv->comp);
txdata |= UNIPHIER_I2C_DTRM_IRQEN;
dev_dbg(&adap->dev, "write data: 0x%04x\n", txdata);
writel(txdata, priv->membase + UNIPHIER_I2C_DTRM);
time_left = wait_for_completion_timeout(&priv->comp, adap->timeout);
if (unlikely(!time_left)) {
dev_err(&adap->dev, "transaction timeout\n");
return -ETIMEDOUT;
}
rxdata = readl(priv->membase + UNIPHIER_I2C_DREC);
dev_dbg(&adap->dev, "read data: 0x%04x\n", rxdata);
if (rxdatap)
*rxdatap = rxdata;
return 0;
}
static int uniphier_i2c_send_byte(struct i2c_adapter *adap, u32 txdata)
{
u32 rxdata;
int ret;
ret = uniphier_i2c_xfer_byte(adap, txdata, &rxdata);
if (ret)
return ret;
if (unlikely(rxdata & UNIPHIER_I2C_DREC_LAB)) {
dev_dbg(&adap->dev, "arbitration lost\n");
return -EAGAIN;
}
if (unlikely(rxdata & UNIPHIER_I2C_DREC_LRB)) {
dev_dbg(&adap->dev, "could not get ACK\n");
return -ENXIO;
}
return 0;
}
static int uniphier_i2c_tx(struct i2c_adapter *adap, u16 addr, u16 len,
const u8 *buf)
{
int ret;
dev_dbg(&adap->dev, "start condition\n");
ret = uniphier_i2c_send_byte(adap, addr << 1 |
UNIPHIER_I2C_DTRM_STA |
UNIPHIER_I2C_DTRM_NACK);
if (ret)
return ret;
while (len--) {
ret = uniphier_i2c_send_byte(adap,
UNIPHIER_I2C_DTRM_NACK | *buf++);
if (ret)
return ret;
}
return 0;
}
static int uniphier_i2c_rx(struct i2c_adapter *adap, u16 addr, u16 len,
u8 *buf)
{
int ret;
dev_dbg(&adap->dev, "start condition\n");
ret = uniphier_i2c_send_byte(adap, addr << 1 |
UNIPHIER_I2C_DTRM_STA |
UNIPHIER_I2C_DTRM_NACK |
UNIPHIER_I2C_DTRM_RD);
if (ret)
return ret;
while (len--) {
u32 rxdata;
ret = uniphier_i2c_xfer_byte(adap,
len ? 0 : UNIPHIER_I2C_DTRM_NACK,
&rxdata);
if (ret)
return ret;
*buf++ = rxdata;
}
return 0;
}
static int uniphier_i2c_stop(struct i2c_adapter *adap)
{
dev_dbg(&adap->dev, "stop condition\n");
return uniphier_i2c_send_byte(adap, UNIPHIER_I2C_DTRM_STO |
UNIPHIER_I2C_DTRM_NACK);
}
static int uniphier_i2c_master_xfer_one(struct i2c_adapter *adap,
struct i2c_msg *msg, bool stop)
{
bool is_read = msg->flags & I2C_M_RD;
bool recovery = false;
int ret;
dev_dbg(&adap->dev, "%s: addr=0x%02x, len=%d, stop=%d\n",
is_read ? "receive" : "transmit", msg->addr, msg->len, stop);
if (is_read)
ret = uniphier_i2c_rx(adap, msg->addr, msg->len, msg->buf);
else
ret = uniphier_i2c_tx(adap, msg->addr, msg->len, msg->buf);
if (ret == -EAGAIN) /* could not acquire bus. bail out without STOP */
return ret;
if (ret == -ETIMEDOUT) {
/* This error is fatal. Needs recovery. */
stop = false;
recovery = true;
}
if (stop) {
int ret2 = uniphier_i2c_stop(adap);
if (ret2) {
/* Failed to issue STOP. The bus needs recovery. */
recovery = true;
ret = ret ?: ret2;
}
}
if (recovery)
i2c_recover_bus(adap);
return ret;
}
static int uniphier_i2c_check_bus_busy(struct i2c_adapter *adap)
{
struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
if (!(readl(priv->membase + UNIPHIER_I2C_DREC) &
UNIPHIER_I2C_DREC_BBN)) {
if (priv->busy_cnt++ > 3) {
/*
* If bus busy continues too long, it is probably
* in a wrong state. Try bus recovery.
*/
i2c_recover_bus(adap);
priv->busy_cnt = 0;
}
return -EAGAIN;
}
priv->busy_cnt = 0;
return 0;
}
static int uniphier_i2c_master_xfer(struct i2c_adapter *adap,
struct i2c_msg *msgs, int num)
{
struct i2c_msg *msg, *emsg = msgs + num;
int ret;
ret = uniphier_i2c_check_bus_busy(adap);
if (ret)
return ret;
for (msg = msgs; msg < emsg; msg++) {
/* If next message is read, skip the stop condition */
bool stop = !(msg + 1 < emsg && msg[1].flags & I2C_M_RD);
/* but, force it if I2C_M_STOP is set */
if (msg->flags & I2C_M_STOP)
stop = true;
ret = uniphier_i2c_master_xfer_one(adap, msg, stop);
if (ret)
return ret;
}
return num;
}
static u32 uniphier_i2c_functionality(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static const struct i2c_algorithm uniphier_i2c_algo = {
.master_xfer = uniphier_i2c_master_xfer,
.functionality = uniphier_i2c_functionality,
};
static void uniphier_i2c_reset(struct uniphier_i2c_priv *priv, bool reset_on)
{
u32 val = UNIPHIER_I2C_BRST_RSCL;
val |= reset_on ? 0 : UNIPHIER_I2C_BRST_FOEN;
writel(val, priv->membase + UNIPHIER_I2C_BRST);
}
static int uniphier_i2c_get_scl(struct i2c_adapter *adap)
{
struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) &
UNIPHIER_I2C_BSTS_SCL);
}
static void uniphier_i2c_set_scl(struct i2c_adapter *adap, int val)
{
struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
writel(val ? UNIPHIER_I2C_BRST_RSCL : 0,
priv->membase + UNIPHIER_I2C_BRST);
}
static int uniphier_i2c_get_sda(struct i2c_adapter *adap)
{
struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) &
UNIPHIER_I2C_BSTS_SDA);
}
static void uniphier_i2c_unprepare_recovery(struct i2c_adapter *adap)
{
uniphier_i2c_reset(i2c_get_adapdata(adap), false);
}
static struct i2c_bus_recovery_info uniphier_i2c_bus_recovery_info = {
.recover_bus = i2c_generic_scl_recovery,
.get_scl = uniphier_i2c_get_scl,
.set_scl = uniphier_i2c_set_scl,
.get_sda = uniphier_i2c_get_sda,
.unprepare_recovery = uniphier_i2c_unprepare_recovery,
};
static int uniphier_i2c_clk_init(struct device *dev,
struct uniphier_i2c_priv *priv)
{
struct device_node *np = dev->of_node;
unsigned long clk_rate;
u32 bus_speed;
int ret;
if (of_property_read_u32(np, "clock-frequency", &bus_speed))
bus_speed = UNIPHIER_I2C_DEFAULT_SPEED;
if (bus_speed > UNIPHIER_I2C_MAX_SPEED)
bus_speed = UNIPHIER_I2C_MAX_SPEED;
/* Get input clk rate through clk driver */
priv->clk = devm_clk_get(dev, NULL);
if (IS_ERR(priv->clk)) {
dev_err(dev, "failed to get clock\n");
return PTR_ERR(priv->clk);
}
ret = clk_prepare_enable(priv->clk);
if (ret)
return ret;
clk_rate = clk_get_rate(priv->clk);
uniphier_i2c_reset(priv, true);
writel((clk_rate / bus_speed / 2 << 16) | (clk_rate / bus_speed),
priv->membase + UNIPHIER_I2C_CLK);
uniphier_i2c_reset(priv, false);
return 0;
}
static int uniphier_i2c_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct uniphier_i2c_priv *priv;
struct resource *regs;
int irq;
int ret;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
priv->membase = devm_ioremap_resource(dev, regs);
if (IS_ERR(priv->membase))
return PTR_ERR(priv->membase);
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
dev_err(dev, "failed to get IRQ number");
return irq;
}
init_completion(&priv->comp);
priv->adap.owner = THIS_MODULE;
priv->adap.algo = &uniphier_i2c_algo;
priv->adap.dev.parent = dev;
priv->adap.dev.of_node = dev->of_node;
strlcpy(priv->adap.name, "UniPhier I2C", sizeof(priv->adap.name));
priv->adap.bus_recovery_info = &uniphier_i2c_bus_recovery_info;
i2c_set_adapdata(&priv->adap, priv);
platform_set_drvdata(pdev, priv);
ret = uniphier_i2c_clk_init(dev, priv);
if (ret)
return ret;
ret = devm_request_irq(dev, irq, uniphier_i2c_interrupt, 0, pdev->name,
priv);
if (ret) {
dev_err(dev, "failed to request irq %d\n", irq);
goto err;
}
ret = i2c_add_adapter(&priv->adap);
if (ret) {
dev_err(dev, "failed to add I2C adapter\n");
goto err;
}
err:
if (ret)
clk_disable_unprepare(priv->clk);
return ret;
}
static int uniphier_i2c_remove(struct platform_device *pdev)
{
struct uniphier_i2c_priv *priv = platform_get_drvdata(pdev);
i2c_del_adapter(&priv->adap);
clk_disable_unprepare(priv->clk);
return 0;
}
static const struct of_device_id uniphier_i2c_match[] = {
{ .compatible = "socionext,uniphier-i2c" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, uniphier_i2c_match);
static struct platform_driver uniphier_i2c_drv = {
.probe = uniphier_i2c_probe,
.remove = uniphier_i2c_remove,
.driver = {
.name = "uniphier-i2c",
.of_match_table = uniphier_i2c_match,
},
};
module_platform_driver(uniphier_i2c_drv);
MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
MODULE_DESCRIPTION("UniPhier I2C bus driver");
MODULE_LICENSE("GPL");