blob: db9105e52c79a1ad7ba0c9b867a617244f40b874 [file] [log] [blame]
/*
* 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/iopoll.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#define UNIPHIER_FI2C_CR 0x00 /* control register */
#define UNIPHIER_FI2C_CR_MST BIT(3) /* master mode */
#define UNIPHIER_FI2C_CR_STA BIT(2) /* start condition */
#define UNIPHIER_FI2C_CR_STO BIT(1) /* stop condition */
#define UNIPHIER_FI2C_CR_NACK BIT(0) /* do not return ACK */
#define UNIPHIER_FI2C_DTTX 0x04 /* TX FIFO */
#define UNIPHIER_FI2C_DTTX_CMD BIT(8) /* send command (slave addr) */
#define UNIPHIER_FI2C_DTTX_RD BIT(0) /* read transaction */
#define UNIPHIER_FI2C_DTRX 0x04 /* RX FIFO */
#define UNIPHIER_FI2C_SLAD 0x0c /* slave address */
#define UNIPHIER_FI2C_CYC 0x10 /* clock cycle control */
#define UNIPHIER_FI2C_LCTL 0x14 /* clock low period control */
#define UNIPHIER_FI2C_SSUT 0x18 /* restart/stop setup time control */
#define UNIPHIER_FI2C_DSUT 0x1c /* data setup time control */
#define UNIPHIER_FI2C_INT 0x20 /* interrupt status */
#define UNIPHIER_FI2C_IE 0x24 /* interrupt enable */
#define UNIPHIER_FI2C_IC 0x28 /* interrupt clear */
#define UNIPHIER_FI2C_INT_TE BIT(9) /* TX FIFO empty */
#define UNIPHIER_FI2C_INT_RF BIT(8) /* RX FIFO full */
#define UNIPHIER_FI2C_INT_TC BIT(7) /* send complete (STOP) */
#define UNIPHIER_FI2C_INT_RC BIT(6) /* receive complete (STOP) */
#define UNIPHIER_FI2C_INT_TB BIT(5) /* sent specified bytes */
#define UNIPHIER_FI2C_INT_RB BIT(4) /* received specified bytes */
#define UNIPHIER_FI2C_INT_NA BIT(2) /* no ACK */
#define UNIPHIER_FI2C_INT_AL BIT(1) /* arbitration lost */
#define UNIPHIER_FI2C_SR 0x2c /* status register */
#define UNIPHIER_FI2C_SR_DB BIT(12) /* device busy */
#define UNIPHIER_FI2C_SR_STS BIT(11) /* stop condition detected */
#define UNIPHIER_FI2C_SR_BB BIT(8) /* bus busy */
#define UNIPHIER_FI2C_SR_RFF BIT(3) /* RX FIFO full */
#define UNIPHIER_FI2C_SR_RNE BIT(2) /* RX FIFO not empty */
#define UNIPHIER_FI2C_SR_TNF BIT(1) /* TX FIFO not full */
#define UNIPHIER_FI2C_SR_TFE BIT(0) /* TX FIFO empty */
#define UNIPHIER_FI2C_RST 0x34 /* reset control */
#define UNIPHIER_FI2C_RST_TBRST BIT(2) /* clear TX FIFO */
#define UNIPHIER_FI2C_RST_RBRST BIT(1) /* clear RX FIFO */
#define UNIPHIER_FI2C_RST_RST BIT(0) /* forcible bus reset */
#define UNIPHIER_FI2C_BM 0x38 /* bus monitor */
#define UNIPHIER_FI2C_BM_SDAO BIT(3) /* output for SDA line */
#define UNIPHIER_FI2C_BM_SDAS BIT(2) /* readback of SDA line */
#define UNIPHIER_FI2C_BM_SCLO BIT(1) /* output for SCL line */
#define UNIPHIER_FI2C_BM_SCLS BIT(0) /* readback of SCL line */
#define UNIPHIER_FI2C_NOISE 0x3c /* noise filter control */
#define UNIPHIER_FI2C_TBC 0x40 /* TX byte count setting */
#define UNIPHIER_FI2C_RBC 0x44 /* RX byte count setting */
#define UNIPHIER_FI2C_TBCM 0x48 /* TX byte count monitor */
#define UNIPHIER_FI2C_RBCM 0x4c /* RX byte count monitor */
#define UNIPHIER_FI2C_BRST 0x50 /* bus reset */
#define UNIPHIER_FI2C_BRST_FOEN BIT(1) /* normal operation */
#define UNIPHIER_FI2C_BRST_RSCL BIT(0) /* release SCL */
#define UNIPHIER_FI2C_INT_FAULTS \
(UNIPHIER_FI2C_INT_NA | UNIPHIER_FI2C_INT_AL)
#define UNIPHIER_FI2C_INT_STOP \
(UNIPHIER_FI2C_INT_TC | UNIPHIER_FI2C_INT_RC)
#define UNIPHIER_FI2C_RD BIT(0)
#define UNIPHIER_FI2C_STOP BIT(1)
#define UNIPHIER_FI2C_MANUAL_NACK BIT(2)
#define UNIPHIER_FI2C_BYTE_WISE BIT(3)
#define UNIPHIER_FI2C_DEFER_STOP_COMP BIT(4)
#define UNIPHIER_FI2C_DEFAULT_SPEED 100000
#define UNIPHIER_FI2C_MAX_SPEED 400000
#define UNIPHIER_FI2C_FIFO_SIZE 8
struct uniphier_fi2c_priv {
struct completion comp;
struct i2c_adapter adap;
void __iomem *membase;
struct clk *clk;
unsigned int len;
u8 *buf;
u32 enabled_irqs;
int error;
unsigned int flags;
unsigned int busy_cnt;
};
static void uniphier_fi2c_fill_txfifo(struct uniphier_fi2c_priv *priv,
bool first)
{
int fifo_space = UNIPHIER_FI2C_FIFO_SIZE;
/*
* TX-FIFO stores slave address in it for the first access.
* Decrement the counter.
*/
if (first)
fifo_space--;
while (priv->len) {
if (fifo_space-- <= 0)
break;
dev_dbg(&priv->adap.dev, "write data: %02x\n", *priv->buf);
writel(*priv->buf++, priv->membase + UNIPHIER_FI2C_DTTX);
priv->len--;
}
}
static void uniphier_fi2c_drain_rxfifo(struct uniphier_fi2c_priv *priv)
{
int fifo_left = priv->flags & UNIPHIER_FI2C_BYTE_WISE ?
1 : UNIPHIER_FI2C_FIFO_SIZE;
while (priv->len) {
if (fifo_left-- <= 0)
break;
*priv->buf++ = readl(priv->membase + UNIPHIER_FI2C_DTRX);
dev_dbg(&priv->adap.dev, "read data: %02x\n", priv->buf[-1]);
priv->len--;
}
}
static void uniphier_fi2c_set_irqs(struct uniphier_fi2c_priv *priv)
{
writel(priv->enabled_irqs, priv->membase + UNIPHIER_FI2C_IE);
}
static void uniphier_fi2c_clear_irqs(struct uniphier_fi2c_priv *priv)
{
writel(-1, priv->membase + UNIPHIER_FI2C_IC);
}
static void uniphier_fi2c_stop(struct uniphier_fi2c_priv *priv)
{
dev_dbg(&priv->adap.dev, "stop condition\n");
priv->enabled_irqs |= UNIPHIER_FI2C_INT_STOP;
uniphier_fi2c_set_irqs(priv);
writel(UNIPHIER_FI2C_CR_MST | UNIPHIER_FI2C_CR_STO,
priv->membase + UNIPHIER_FI2C_CR);
}
static irqreturn_t uniphier_fi2c_interrupt(int irq, void *dev_id)
{
struct uniphier_fi2c_priv *priv = dev_id;
u32 irq_status;
irq_status = readl(priv->membase + UNIPHIER_FI2C_INT);
dev_dbg(&priv->adap.dev,
"interrupt: enabled_irqs=%04x, irq_status=%04x\n",
priv->enabled_irqs, irq_status);
if (irq_status & UNIPHIER_FI2C_INT_STOP)
goto complete;
if (unlikely(irq_status & UNIPHIER_FI2C_INT_AL)) {
dev_dbg(&priv->adap.dev, "arbitration lost\n");
priv->error = -EAGAIN;
goto complete;
}
if (unlikely(irq_status & UNIPHIER_FI2C_INT_NA)) {
dev_dbg(&priv->adap.dev, "could not get ACK\n");
priv->error = -ENXIO;
if (priv->flags & UNIPHIER_FI2C_RD) {
/*
* work around a hardware bug:
* The receive-completed interrupt is never set even if
* STOP condition is detected after the address phase
* of read transaction fails to get ACK.
* To avoid time-out error, we issue STOP here,
* but do not wait for its completion.
* It should be checked after exiting this handler.
*/
uniphier_fi2c_stop(priv);
priv->flags |= UNIPHIER_FI2C_DEFER_STOP_COMP;
goto complete;
}
goto stop;
}
if (irq_status & UNIPHIER_FI2C_INT_TE) {
if (!priv->len)
goto data_done;
uniphier_fi2c_fill_txfifo(priv, false);
goto handled;
}
if (irq_status & (UNIPHIER_FI2C_INT_RF | UNIPHIER_FI2C_INT_RB)) {
uniphier_fi2c_drain_rxfifo(priv);
if (!priv->len)
goto data_done;
if (unlikely(priv->flags & UNIPHIER_FI2C_MANUAL_NACK)) {
if (priv->len <= UNIPHIER_FI2C_FIFO_SIZE &&
!(priv->flags & UNIPHIER_FI2C_BYTE_WISE)) {
dev_dbg(&priv->adap.dev,
"enable read byte count IRQ\n");
priv->enabled_irqs |= UNIPHIER_FI2C_INT_RB;
uniphier_fi2c_set_irqs(priv);
priv->flags |= UNIPHIER_FI2C_BYTE_WISE;
}
if (priv->len <= 1) {
dev_dbg(&priv->adap.dev, "set NACK\n");
writel(UNIPHIER_FI2C_CR_MST |
UNIPHIER_FI2C_CR_NACK,
priv->membase + UNIPHIER_FI2C_CR);
}
}
goto handled;
}
return IRQ_NONE;
data_done:
if (priv->flags & UNIPHIER_FI2C_STOP) {
stop:
uniphier_fi2c_stop(priv);
} else {
complete:
priv->enabled_irqs = 0;
uniphier_fi2c_set_irqs(priv);
complete(&priv->comp);
}
handled:
uniphier_fi2c_clear_irqs(priv);
return IRQ_HANDLED;
}
static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr)
{
priv->enabled_irqs |= UNIPHIER_FI2C_INT_TE;
/* do not use TX byte counter */
writel(0, priv->membase + UNIPHIER_FI2C_TBC);
/* set slave address */
writel(UNIPHIER_FI2C_DTTX_CMD | addr << 1,
priv->membase + UNIPHIER_FI2C_DTTX);
/* first chunk of data */
uniphier_fi2c_fill_txfifo(priv, true);
}
static void uniphier_fi2c_rx_init(struct uniphier_fi2c_priv *priv, u16 addr)
{
priv->flags |= UNIPHIER_FI2C_RD;
if (likely(priv->len < 256)) {
/*
* If possible, use RX byte counter.
* It can automatically handle NACK for the last byte.
*/
writel(priv->len, priv->membase + UNIPHIER_FI2C_RBC);
priv->enabled_irqs |= UNIPHIER_FI2C_INT_RF |
UNIPHIER_FI2C_INT_RB;
} else {
/*
* The byte counter can not count over 256. In this case,
* do not use it at all. Drain data when FIFO gets full,
* but treat the last portion as a special case.
*/
writel(0, priv->membase + UNIPHIER_FI2C_RBC);
priv->flags |= UNIPHIER_FI2C_MANUAL_NACK;
priv->enabled_irqs |= UNIPHIER_FI2C_INT_RF;
}
/* set slave address with RD bit */
writel(UNIPHIER_FI2C_DTTX_CMD | UNIPHIER_FI2C_DTTX_RD | addr << 1,
priv->membase + UNIPHIER_FI2C_DTTX);
}
static void uniphier_fi2c_reset(struct uniphier_fi2c_priv *priv)
{
writel(UNIPHIER_FI2C_RST_RST, priv->membase + UNIPHIER_FI2C_RST);
}
static void uniphier_fi2c_prepare_operation(struct uniphier_fi2c_priv *priv)
{
writel(UNIPHIER_FI2C_BRST_FOEN | UNIPHIER_FI2C_BRST_RSCL,
priv->membase + UNIPHIER_FI2C_BRST);
}
static void uniphier_fi2c_recover(struct uniphier_fi2c_priv *priv)
{
uniphier_fi2c_reset(priv);
i2c_recover_bus(&priv->adap);
}
static int uniphier_fi2c_master_xfer_one(struct i2c_adapter *adap,
struct i2c_msg *msg, bool stop)
{
struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
bool is_read = msg->flags & I2C_M_RD;
unsigned long time_left;
dev_dbg(&adap->dev, "%s: addr=0x%02x, len=%d, stop=%d\n",
is_read ? "receive" : "transmit", msg->addr, msg->len, stop);
priv->len = msg->len;
priv->buf = msg->buf;
priv->enabled_irqs = UNIPHIER_FI2C_INT_FAULTS;
priv->error = 0;
priv->flags = 0;
if (stop)
priv->flags |= UNIPHIER_FI2C_STOP;
reinit_completion(&priv->comp);
uniphier_fi2c_clear_irqs(priv);
writel(UNIPHIER_FI2C_RST_TBRST | UNIPHIER_FI2C_RST_RBRST,
priv->membase + UNIPHIER_FI2C_RST); /* reset TX/RX FIFO */
if (is_read)
uniphier_fi2c_rx_init(priv, msg->addr);
else
uniphier_fi2c_tx_init(priv, msg->addr);
uniphier_fi2c_set_irqs(priv);
dev_dbg(&adap->dev, "start condition\n");
writel(UNIPHIER_FI2C_CR_MST | UNIPHIER_FI2C_CR_STA,
priv->membase + UNIPHIER_FI2C_CR);
time_left = wait_for_completion_timeout(&priv->comp, adap->timeout);
if (!time_left) {
dev_err(&adap->dev, "transaction timeout.\n");
uniphier_fi2c_recover(priv);
return -ETIMEDOUT;
}
dev_dbg(&adap->dev, "complete\n");
if (unlikely(priv->flags & UNIPHIER_FI2C_DEFER_STOP_COMP)) {
u32 status;
int ret;
ret = readl_poll_timeout(priv->membase + UNIPHIER_FI2C_SR,
status,
(status & UNIPHIER_FI2C_SR_STS) &&
!(status & UNIPHIER_FI2C_SR_BB),
1, 20);
if (ret) {
dev_err(&adap->dev,
"stop condition was not completed.\n");
uniphier_fi2c_recover(priv);
return ret;
}
}
return priv->error;
}
static int uniphier_fi2c_check_bus_busy(struct i2c_adapter *adap)
{
struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
if (readl(priv->membase + UNIPHIER_FI2C_SR) & UNIPHIER_FI2C_SR_DB) {
if (priv->busy_cnt++ > 3) {
/*
* If bus busy continues too long, it is probably
* in a wrong state. Try bus recovery.
*/
uniphier_fi2c_recover(priv);
priv->busy_cnt = 0;
}
return -EAGAIN;
}
priv->busy_cnt = 0;
return 0;
}
static int uniphier_fi2c_master_xfer(struct i2c_adapter *adap,
struct i2c_msg *msgs, int num)
{
struct i2c_msg *msg, *emsg = msgs + num;
int ret;
ret = uniphier_fi2c_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_fi2c_master_xfer_one(adap, msg, stop);
if (ret)
return ret;
}
return num;
}
static u32 uniphier_fi2c_functionality(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static const struct i2c_algorithm uniphier_fi2c_algo = {
.master_xfer = uniphier_fi2c_master_xfer,
.functionality = uniphier_fi2c_functionality,
};
static int uniphier_fi2c_get_scl(struct i2c_adapter *adap)
{
struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
return !!(readl(priv->membase + UNIPHIER_FI2C_BM) &
UNIPHIER_FI2C_BM_SCLS);
}
static void uniphier_fi2c_set_scl(struct i2c_adapter *adap, int val)
{
struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
writel(val ? UNIPHIER_FI2C_BRST_RSCL : 0,
priv->membase + UNIPHIER_FI2C_BRST);
}
static int uniphier_fi2c_get_sda(struct i2c_adapter *adap)
{
struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
return !!(readl(priv->membase + UNIPHIER_FI2C_BM) &
UNIPHIER_FI2C_BM_SDAS);
}
static void uniphier_fi2c_unprepare_recovery(struct i2c_adapter *adap)
{
uniphier_fi2c_prepare_operation(i2c_get_adapdata(adap));
}
static struct i2c_bus_recovery_info uniphier_fi2c_bus_recovery_info = {
.recover_bus = i2c_generic_scl_recovery,
.get_scl = uniphier_fi2c_get_scl,
.set_scl = uniphier_fi2c_set_scl,
.get_sda = uniphier_fi2c_get_sda,
.unprepare_recovery = uniphier_fi2c_unprepare_recovery,
};
static void uniphier_fi2c_hw_init(struct uniphier_fi2c_priv *priv,
u32 bus_speed, unsigned long clk_rate)
{
u32 tmp;
tmp = readl(priv->membase + UNIPHIER_FI2C_CR);
tmp |= UNIPHIER_FI2C_CR_MST;
writel(tmp, priv->membase + UNIPHIER_FI2C_CR);
uniphier_fi2c_reset(priv);
tmp = clk_rate / bus_speed;
writel(tmp, priv->membase + UNIPHIER_FI2C_CYC);
writel(tmp / 2, priv->membase + UNIPHIER_FI2C_LCTL);
writel(tmp / 2, priv->membase + UNIPHIER_FI2C_SSUT);
writel(tmp / 16, priv->membase + UNIPHIER_FI2C_DSUT);
uniphier_fi2c_prepare_operation(priv);
}
static int uniphier_fi2c_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct uniphier_fi2c_priv *priv;
struct resource *regs;
u32 bus_speed;
unsigned long clk_rate;
int irq, 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\n");
return irq;
}
if (of_property_read_u32(dev->of_node, "clock-frequency", &bus_speed))
bus_speed = UNIPHIER_FI2C_DEFAULT_SPEED;
if (!bus_speed || bus_speed > UNIPHIER_FI2C_MAX_SPEED) {
dev_err(dev, "invalid clock-frequency %d\n", bus_speed);
return -EINVAL;
}
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);
if (!clk_rate) {
dev_err(dev, "input clock rate should not be zero\n");
ret = -EINVAL;
goto err;
}
init_completion(&priv->comp);
priv->adap.owner = THIS_MODULE;
priv->adap.algo = &uniphier_fi2c_algo;
priv->adap.dev.parent = dev;
priv->adap.dev.of_node = dev->of_node;
strlcpy(priv->adap.name, "UniPhier FI2C", sizeof(priv->adap.name));
priv->adap.bus_recovery_info = &uniphier_fi2c_bus_recovery_info;
i2c_set_adapdata(&priv->adap, priv);
platform_set_drvdata(pdev, priv);
uniphier_fi2c_hw_init(priv, bus_speed, clk_rate);
ret = devm_request_irq(dev, irq, uniphier_fi2c_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);
err:
if (ret)
clk_disable_unprepare(priv->clk);
return ret;
}
static int uniphier_fi2c_remove(struct platform_device *pdev)
{
struct uniphier_fi2c_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_fi2c_match[] = {
{ .compatible = "socionext,uniphier-fi2c" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, uniphier_fi2c_match);
static struct platform_driver uniphier_fi2c_drv = {
.probe = uniphier_fi2c_probe,
.remove = uniphier_fi2c_remove,
.driver = {
.name = "uniphier-fi2c",
.of_match_table = uniphier_fi2c_match,
},
};
module_platform_driver(uniphier_fi2c_drv);
MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
MODULE_DESCRIPTION("UniPhier FIFO-builtin I2C bus driver");
MODULE_LICENSE("GPL");