510 lines
12 KiB
C
510 lines
12 KiB
C
/*
|
|
* Copyright (C) 2011 NXP Semiconductors
|
|
*
|
|
* Code portions referenced from the i2x-pxa and i2c-pnx drivers
|
|
*
|
|
* Make SMBus byte and word transactions work on LPC178x/7x
|
|
* Copyright (c) 2012
|
|
* Alexander Potashev, Emcraft Systems, aspotashev@emcraft.com
|
|
* Anton Protopopov, Emcraft Systems, antonp@emcraft.com
|
|
*
|
|
* Copyright (C) 2015 Joachim Eastwood <manabian@gmail.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.
|
|
*
|
|
*/
|
|
|
|
#include <linux/clk.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/i2c.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/io.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/of.h>
|
|
#include <linux/of_device.h>
|
|
#include <linux/platform_device.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/time.h>
|
|
|
|
/* LPC24xx register offsets and bits */
|
|
#define LPC24XX_I2CONSET 0x00
|
|
#define LPC24XX_I2STAT 0x04
|
|
#define LPC24XX_I2DAT 0x08
|
|
#define LPC24XX_I2ADDR 0x0c
|
|
#define LPC24XX_I2SCLH 0x10
|
|
#define LPC24XX_I2SCLL 0x14
|
|
#define LPC24XX_I2CONCLR 0x18
|
|
|
|
#define LPC24XX_AA BIT(2)
|
|
#define LPC24XX_SI BIT(3)
|
|
#define LPC24XX_STO BIT(4)
|
|
#define LPC24XX_STA BIT(5)
|
|
#define LPC24XX_I2EN BIT(6)
|
|
|
|
#define LPC24XX_STO_AA (LPC24XX_STO | LPC24XX_AA)
|
|
#define LPC24XX_CLEAR_ALL (LPC24XX_AA | LPC24XX_SI | LPC24XX_STO | \
|
|
LPC24XX_STA | LPC24XX_I2EN)
|
|
|
|
/* I2C SCL clock has different duty cycle depending on mode */
|
|
#define I2C_STD_MODE_DUTY 46
|
|
#define I2C_FAST_MODE_DUTY 36
|
|
#define I2C_FAST_MODE_PLUS_DUTY 38
|
|
|
|
/*
|
|
* 26 possible I2C status codes, but codes applicable only
|
|
* to master are listed here and used in this driver
|
|
*/
|
|
enum {
|
|
M_BUS_ERROR = 0x00,
|
|
M_START = 0x08,
|
|
M_REPSTART = 0x10,
|
|
MX_ADDR_W_ACK = 0x18,
|
|
MX_ADDR_W_NACK = 0x20,
|
|
MX_DATA_W_ACK = 0x28,
|
|
MX_DATA_W_NACK = 0x30,
|
|
M_DATA_ARB_LOST = 0x38,
|
|
MR_ADDR_R_ACK = 0x40,
|
|
MR_ADDR_R_NACK = 0x48,
|
|
MR_DATA_R_ACK = 0x50,
|
|
MR_DATA_R_NACK = 0x58,
|
|
M_I2C_IDLE = 0xf8,
|
|
};
|
|
|
|
struct lpc2k_i2c {
|
|
void __iomem *base;
|
|
struct clk *clk;
|
|
int irq;
|
|
wait_queue_head_t wait;
|
|
struct i2c_adapter adap;
|
|
struct i2c_msg *msg;
|
|
int msg_idx;
|
|
int msg_status;
|
|
int is_last;
|
|
};
|
|
|
|
static void i2c_lpc2k_reset(struct lpc2k_i2c *i2c)
|
|
{
|
|
/* Will force clear all statuses */
|
|
writel(LPC24XX_CLEAR_ALL, i2c->base + LPC24XX_I2CONCLR);
|
|
writel(0, i2c->base + LPC24XX_I2ADDR);
|
|
writel(LPC24XX_I2EN, i2c->base + LPC24XX_I2CONSET);
|
|
}
|
|
|
|
static int i2c_lpc2k_clear_arb(struct lpc2k_i2c *i2c)
|
|
{
|
|
unsigned long timeout = jiffies + msecs_to_jiffies(1000);
|
|
|
|
/*
|
|
* If the transfer needs to abort for some reason, we'll try to
|
|
* force a stop condition to clear any pending bus conditions
|
|
*/
|
|
writel(LPC24XX_STO, i2c->base + LPC24XX_I2CONSET);
|
|
|
|
/* Wait for status change */
|
|
while (readl(i2c->base + LPC24XX_I2STAT) != M_I2C_IDLE) {
|
|
if (time_after(jiffies, timeout)) {
|
|
/* Bus was not idle, try to reset adapter */
|
|
i2c_lpc2k_reset(i2c);
|
|
return -EBUSY;
|
|
}
|
|
|
|
cpu_relax();
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void i2c_lpc2k_pump_msg(struct lpc2k_i2c *i2c)
|
|
{
|
|
unsigned char data;
|
|
u32 status;
|
|
|
|
/*
|
|
* I2C in the LPC2xxx series is basically a state machine.
|
|
* Just run through the steps based on the current status.
|
|
*/
|
|
status = readl(i2c->base + LPC24XX_I2STAT);
|
|
|
|
switch (status) {
|
|
case M_START:
|
|
case M_REPSTART:
|
|
/* Start bit was just sent out, send out addr and dir */
|
|
data = i2c_8bit_addr_from_msg(i2c->msg);
|
|
|
|
writel(data, i2c->base + LPC24XX_I2DAT);
|
|
writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONCLR);
|
|
break;
|
|
|
|
case MX_ADDR_W_ACK:
|
|
case MX_DATA_W_ACK:
|
|
/*
|
|
* Address or data was sent out with an ACK. If there is more
|
|
* data to send, send it now
|
|
*/
|
|
if (i2c->msg_idx < i2c->msg->len) {
|
|
writel(i2c->msg->buf[i2c->msg_idx],
|
|
i2c->base + LPC24XX_I2DAT);
|
|
} else if (i2c->is_last) {
|
|
/* Last message, send stop */
|
|
writel(LPC24XX_STO_AA, i2c->base + LPC24XX_I2CONSET);
|
|
writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR);
|
|
i2c->msg_status = 0;
|
|
disable_irq_nosync(i2c->irq);
|
|
} else {
|
|
i2c->msg_status = 0;
|
|
disable_irq_nosync(i2c->irq);
|
|
}
|
|
|
|
i2c->msg_idx++;
|
|
break;
|
|
|
|
case MR_ADDR_R_ACK:
|
|
/* Receive first byte from slave */
|
|
if (i2c->msg->len == 1) {
|
|
/* Last byte, return NACK */
|
|
writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONCLR);
|
|
} else {
|
|
/* Not last byte, return ACK */
|
|
writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONSET);
|
|
}
|
|
|
|
writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONCLR);
|
|
break;
|
|
|
|
case MR_DATA_R_NACK:
|
|
/*
|
|
* The I2C shows NACK status on reads, so we need to accept
|
|
* the NACK as an ACK here. This should be ok, as the real
|
|
* BACK would of been caught on the address write.
|
|
*/
|
|
case MR_DATA_R_ACK:
|
|
/* Data was received */
|
|
if (i2c->msg_idx < i2c->msg->len) {
|
|
i2c->msg->buf[i2c->msg_idx] =
|
|
readl(i2c->base + LPC24XX_I2DAT);
|
|
}
|
|
|
|
/* If transfer is done, send STOP */
|
|
if (i2c->msg_idx >= i2c->msg->len - 1 && i2c->is_last) {
|
|
writel(LPC24XX_STO_AA, i2c->base + LPC24XX_I2CONSET);
|
|
writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR);
|
|
i2c->msg_status = 0;
|
|
}
|
|
|
|
/* Message is done */
|
|
if (i2c->msg_idx >= i2c->msg->len - 1) {
|
|
i2c->msg_status = 0;
|
|
disable_irq_nosync(i2c->irq);
|
|
}
|
|
|
|
/*
|
|
* One pre-last data input, send NACK to tell the slave that
|
|
* this is going to be the last data byte to be transferred.
|
|
*/
|
|
if (i2c->msg_idx >= i2c->msg->len - 2) {
|
|
/* One byte left to receive - NACK */
|
|
writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONCLR);
|
|
} else {
|
|
/* More than one byte left to receive - ACK */
|
|
writel(LPC24XX_AA, i2c->base + LPC24XX_I2CONSET);
|
|
}
|
|
|
|
writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONCLR);
|
|
i2c->msg_idx++;
|
|
break;
|
|
|
|
case MX_ADDR_W_NACK:
|
|
case MX_DATA_W_NACK:
|
|
case MR_ADDR_R_NACK:
|
|
/* NACK processing is done */
|
|
writel(LPC24XX_STO_AA, i2c->base + LPC24XX_I2CONSET);
|
|
i2c->msg_status = -ENXIO;
|
|
disable_irq_nosync(i2c->irq);
|
|
break;
|
|
|
|
case M_DATA_ARB_LOST:
|
|
/* Arbitration lost */
|
|
i2c->msg_status = -EAGAIN;
|
|
|
|
/* Release the I2C bus */
|
|
writel(LPC24XX_STA | LPC24XX_STO, i2c->base + LPC24XX_I2CONCLR);
|
|
disable_irq_nosync(i2c->irq);
|
|
break;
|
|
|
|
default:
|
|
/* Unexpected statuses */
|
|
i2c->msg_status = -EIO;
|
|
disable_irq_nosync(i2c->irq);
|
|
break;
|
|
}
|
|
|
|
/* Exit on failure or all bytes transferred */
|
|
if (i2c->msg_status != -EBUSY)
|
|
wake_up(&i2c->wait);
|
|
|
|
/*
|
|
* If `msg_status` is zero, then `lpc2k_process_msg()`
|
|
* is responsible for clearing the SI flag.
|
|
*/
|
|
if (i2c->msg_status != 0)
|
|
writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR);
|
|
}
|
|
|
|
static int lpc2k_process_msg(struct lpc2k_i2c *i2c, int msgidx)
|
|
{
|
|
/* A new transfer is kicked off by initiating a start condition */
|
|
if (!msgidx) {
|
|
writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONSET);
|
|
} else {
|
|
/*
|
|
* A multi-message I2C transfer continues where the
|
|
* previous I2C transfer left off and uses the
|
|
* current condition of the I2C adapter.
|
|
*/
|
|
if (unlikely(i2c->msg->flags & I2C_M_NOSTART)) {
|
|
WARN_ON(i2c->msg->len == 0);
|
|
|
|
if (!(i2c->msg->flags & I2C_M_RD)) {
|
|
/* Start transmit of data */
|
|
writel(i2c->msg->buf[0],
|
|
i2c->base + LPC24XX_I2DAT);
|
|
i2c->msg_idx++;
|
|
}
|
|
} else {
|
|
/* Start or repeated start */
|
|
writel(LPC24XX_STA, i2c->base + LPC24XX_I2CONSET);
|
|
}
|
|
|
|
writel(LPC24XX_SI, i2c->base + LPC24XX_I2CONCLR);
|
|
}
|
|
|
|
enable_irq(i2c->irq);
|
|
|
|
/* Wait for transfer completion */
|
|
if (wait_event_timeout(i2c->wait, i2c->msg_status != -EBUSY,
|
|
msecs_to_jiffies(1000)) == 0) {
|
|
disable_irq_nosync(i2c->irq);
|
|
|
|
return -ETIMEDOUT;
|
|
}
|
|
|
|
return i2c->msg_status;
|
|
}
|
|
|
|
static int i2c_lpc2k_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
|
|
int msg_num)
|
|
{
|
|
struct lpc2k_i2c *i2c = i2c_get_adapdata(adap);
|
|
int ret, i;
|
|
u32 stat;
|
|
|
|
/* Check for bus idle condition */
|
|
stat = readl(i2c->base + LPC24XX_I2STAT);
|
|
if (stat != M_I2C_IDLE) {
|
|
/* Something is holding the bus, try to clear it */
|
|
return i2c_lpc2k_clear_arb(i2c);
|
|
}
|
|
|
|
/* Process a single message at a time */
|
|
for (i = 0; i < msg_num; i++) {
|
|
/* Save message pointer and current message data index */
|
|
i2c->msg = &msgs[i];
|
|
i2c->msg_idx = 0;
|
|
i2c->msg_status = -EBUSY;
|
|
i2c->is_last = (i == (msg_num - 1));
|
|
|
|
ret = lpc2k_process_msg(i2c, i);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
return msg_num;
|
|
}
|
|
|
|
static irqreturn_t i2c_lpc2k_handler(int irq, void *dev_id)
|
|
{
|
|
struct lpc2k_i2c *i2c = dev_id;
|
|
|
|
if (readl(i2c->base + LPC24XX_I2CONSET) & LPC24XX_SI) {
|
|
i2c_lpc2k_pump_msg(i2c);
|
|
return IRQ_HANDLED;
|
|
}
|
|
|
|
return IRQ_NONE;
|
|
}
|
|
|
|
static u32 i2c_lpc2k_functionality(struct i2c_adapter *adap)
|
|
{
|
|
/* Only emulated SMBus for now */
|
|
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
|
|
}
|
|
|
|
static const struct i2c_algorithm i2c_lpc2k_algorithm = {
|
|
.master_xfer = i2c_lpc2k_xfer,
|
|
.functionality = i2c_lpc2k_functionality,
|
|
};
|
|
|
|
static int i2c_lpc2k_probe(struct platform_device *pdev)
|
|
{
|
|
struct lpc2k_i2c *i2c;
|
|
struct resource *res;
|
|
u32 bus_clk_rate;
|
|
u32 scl_high;
|
|
u32 clkrate;
|
|
int ret;
|
|
|
|
i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
|
|
if (!i2c)
|
|
return -ENOMEM;
|
|
|
|
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
|
|
i2c->base = devm_ioremap_resource(&pdev->dev, res);
|
|
if (IS_ERR(i2c->base))
|
|
return PTR_ERR(i2c->base);
|
|
|
|
i2c->irq = platform_get_irq(pdev, 0);
|
|
if (i2c->irq < 0) {
|
|
dev_err(&pdev->dev, "can't get interrupt resource\n");
|
|
return i2c->irq;
|
|
}
|
|
|
|
init_waitqueue_head(&i2c->wait);
|
|
|
|
i2c->clk = devm_clk_get(&pdev->dev, NULL);
|
|
if (IS_ERR(i2c->clk)) {
|
|
dev_err(&pdev->dev, "error getting clock\n");
|
|
return PTR_ERR(i2c->clk);
|
|
}
|
|
|
|
ret = clk_prepare_enable(i2c->clk);
|
|
if (ret) {
|
|
dev_err(&pdev->dev, "unable to enable clock.\n");
|
|
return ret;
|
|
}
|
|
|
|
ret = devm_request_irq(&pdev->dev, i2c->irq, i2c_lpc2k_handler, 0,
|
|
dev_name(&pdev->dev), i2c);
|
|
if (ret < 0) {
|
|
dev_err(&pdev->dev, "can't request interrupt.\n");
|
|
goto fail_clk;
|
|
}
|
|
|
|
disable_irq_nosync(i2c->irq);
|
|
|
|
/* Place controller is a known state */
|
|
i2c_lpc2k_reset(i2c);
|
|
|
|
ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
|
|
&bus_clk_rate);
|
|
if (ret)
|
|
bus_clk_rate = 100000; /* 100 kHz default clock rate */
|
|
|
|
clkrate = clk_get_rate(i2c->clk);
|
|
if (clkrate == 0) {
|
|
dev_err(&pdev->dev, "can't get I2C base clock\n");
|
|
ret = -EINVAL;
|
|
goto fail_clk;
|
|
}
|
|
|
|
/* Setup I2C dividers to generate clock with proper duty cycle */
|
|
clkrate = clkrate / bus_clk_rate;
|
|
if (bus_clk_rate <= 100000)
|
|
scl_high = (clkrate * I2C_STD_MODE_DUTY) / 100;
|
|
else if (bus_clk_rate <= 400000)
|
|
scl_high = (clkrate * I2C_FAST_MODE_DUTY) / 100;
|
|
else
|
|
scl_high = (clkrate * I2C_FAST_MODE_PLUS_DUTY) / 100;
|
|
|
|
writel(scl_high, i2c->base + LPC24XX_I2SCLH);
|
|
writel(clkrate - scl_high, i2c->base + LPC24XX_I2SCLL);
|
|
|
|
platform_set_drvdata(pdev, i2c);
|
|
|
|
i2c_set_adapdata(&i2c->adap, i2c);
|
|
i2c->adap.owner = THIS_MODULE;
|
|
strlcpy(i2c->adap.name, "LPC2K I2C adapter", sizeof(i2c->adap.name));
|
|
i2c->adap.algo = &i2c_lpc2k_algorithm;
|
|
i2c->adap.dev.parent = &pdev->dev;
|
|
i2c->adap.dev.of_node = pdev->dev.of_node;
|
|
|
|
ret = i2c_add_adapter(&i2c->adap);
|
|
if (ret < 0)
|
|
goto fail_clk;
|
|
|
|
dev_info(&pdev->dev, "LPC2K I2C adapter\n");
|
|
|
|
return 0;
|
|
|
|
fail_clk:
|
|
clk_disable_unprepare(i2c->clk);
|
|
return ret;
|
|
}
|
|
|
|
static int i2c_lpc2k_remove(struct platform_device *dev)
|
|
{
|
|
struct lpc2k_i2c *i2c = platform_get_drvdata(dev);
|
|
|
|
i2c_del_adapter(&i2c->adap);
|
|
clk_disable_unprepare(i2c->clk);
|
|
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_PM
|
|
static int i2c_lpc2k_suspend(struct device *dev)
|
|
{
|
|
struct platform_device *pdev = to_platform_device(dev);
|
|
struct lpc2k_i2c *i2c = platform_get_drvdata(pdev);
|
|
|
|
clk_disable(i2c->clk);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int i2c_lpc2k_resume(struct device *dev)
|
|
{
|
|
struct platform_device *pdev = to_platform_device(dev);
|
|
struct lpc2k_i2c *i2c = platform_get_drvdata(pdev);
|
|
|
|
clk_enable(i2c->clk);
|
|
i2c_lpc2k_reset(i2c);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct dev_pm_ops i2c_lpc2k_dev_pm_ops = {
|
|
.suspend_noirq = i2c_lpc2k_suspend,
|
|
.resume_noirq = i2c_lpc2k_resume,
|
|
};
|
|
|
|
#define I2C_LPC2K_DEV_PM_OPS (&i2c_lpc2k_dev_pm_ops)
|
|
#else
|
|
#define I2C_LPC2K_DEV_PM_OPS NULL
|
|
#endif
|
|
|
|
static const struct of_device_id lpc2k_i2c_match[] = {
|
|
{ .compatible = "nxp,lpc1788-i2c" },
|
|
{},
|
|
};
|
|
MODULE_DEVICE_TABLE(of, lpc2k_i2c_match);
|
|
|
|
static struct platform_driver i2c_lpc2k_driver = {
|
|
.probe = i2c_lpc2k_probe,
|
|
.remove = i2c_lpc2k_remove,
|
|
.driver = {
|
|
.name = "lpc2k-i2c",
|
|
.pm = I2C_LPC2K_DEV_PM_OPS,
|
|
.of_match_table = lpc2k_i2c_match,
|
|
},
|
|
};
|
|
module_platform_driver(i2c_lpc2k_driver);
|
|
|
|
MODULE_AUTHOR("Kevin Wells <kevin.wells@nxp.com>");
|
|
MODULE_DESCRIPTION("I2C driver for LPC2xxx devices");
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_ALIAS("platform:lpc2k-i2c");
|