- 根目录:
- drivers
- i2c
- busses
- i2c-mxs.c
/*
* Freescale MXS I2C bus driver
*
* Copyright (C) 2011 Wolfram Sang, Pengutronix e.K.
*
* based on a (non-working) driver which was:
*
* Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
*
* TODO: add dma-support if platform-support for it is available
*
* 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/slab.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/completion.h>
#include <linux/platform_device.h>
#include <linux/jiffies.h>
#include <linux/io.h>
#include <mach/common.h>
#define DRIVER_NAME "mxs-i2c"
#define MXS_I2C_CTRL0 (0x00)
#define MXS_I2C_CTRL0_SET (0x04)
#define MXS_I2C_CTRL0_SFTRST 0x80000000
#define MXS_I2C_CTRL0_SEND_NAK_ON_LAST 0x02000000
#define MXS_I2C_CTRL0_RETAIN_CLOCK 0x00200000
#define MXS_I2C_CTRL0_POST_SEND_STOP 0x00100000
#define MXS_I2C_CTRL0_PRE_SEND_START 0x00080000
#define MXS_I2C_CTRL0_MASTER_MODE 0x00020000
#define MXS_I2C_CTRL0_DIRECTION 0x00010000
#define MXS_I2C_CTRL0_XFER_COUNT(v) ((v) & 0x0000FFFF)
#define MXS_I2C_CTRL1 (0x40)
#define MXS_I2C_CTRL1_SET (0x44)
#define MXS_I2C_CTRL1_CLR (0x48)
#define MXS_I2C_CTRL1_BUS_FREE_IRQ 0x80
#define MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ 0x40
#define MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ 0x20
#define MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ 0x10
#define MXS_I2C_CTRL1_EARLY_TERM_IRQ 0x08
#define MXS_I2C_CTRL1_MASTER_LOSS_IRQ 0x04
#define MXS_I2C_CTRL1_SLAVE_STOP_IRQ 0x02
#define MXS_I2C_CTRL1_SLAVE_IRQ 0x01
#define MXS_I2C_IRQ_MASK (MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ | \
MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ | \
MXS_I2C_CTRL1_EARLY_TERM_IRQ | \
MXS_I2C_CTRL1_MASTER_LOSS_IRQ | \
MXS_I2C_CTRL1_SLAVE_STOP_IRQ | \
MXS_I2C_CTRL1_SLAVE_IRQ)
#define MXS_I2C_QUEUECTRL (0x60)
#define MXS_I2C_QUEUECTRL_SET (0x64)
#define MXS_I2C_QUEUECTRL_CLR (0x68)
#define MXS_I2C_QUEUECTRL_QUEUE_RUN 0x20
#define MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE 0x04
#define MXS_I2C_QUEUESTAT (0x70)
#define MXS_I2C_QUEUESTAT_RD_QUEUE_EMPTY 0x00002000
#define MXS_I2C_QUEUESTAT_WRITE_QUEUE_CNT_MASK 0x0000001F
#define MXS_I2C_QUEUECMD (0x80)
#define MXS_I2C_QUEUEDATA (0x90)
#define MXS_I2C_DATA (0xa0)
#define MXS_CMD_I2C_SELECT (MXS_I2C_CTRL0_RETAIN_CLOCK | \
MXS_I2C_CTRL0_PRE_SEND_START | \
MXS_I2C_CTRL0_MASTER_MODE | \
MXS_I2C_CTRL0_DIRECTION | \
MXS_I2C_CTRL0_XFER_COUNT(1))
#define MXS_CMD_I2C_WRITE (MXS_I2C_CTRL0_PRE_SEND_START | \
MXS_I2C_CTRL0_MASTER_MODE | \
MXS_I2C_CTRL0_DIRECTION)
#define MXS_CMD_I2C_READ (MXS_I2C_CTRL0_SEND_NAK_ON_LAST | \
MXS_I2C_CTRL0_MASTER_MODE)
/**
* struct mxs_i2c_dev - per device, private MXS-I2C data
*
* @dev: driver model device node
* @regs: IO registers pointer
* @cmd_complete: completion object for transaction wait
* @cmd_err: error code for last transaction
* @adapter: i2c subsystem adapter node
*/
struct mxs_i2c_dev {
struct device *dev;
void __iomem *regs;
struct completion cmd_complete;
u32 cmd_err;
struct i2c_adapter adapter;
};
/*
* TODO: check if calls to here are really needed. If not, we could get rid of
* mxs_reset_block and the mach-dependency. Needs an I2C analyzer, probably.
*/
static void mxs_i2c_reset(struct mxs_i2c_dev *i2c)
{
mxs_reset_block(i2c->regs);
writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
writel(MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE,
i2c->regs + MXS_I2C_QUEUECTRL_SET);
}
static void mxs_i2c_pioq_setup_read(struct mxs_i2c_dev *i2c, u8 addr, int len,
int flags)
{
u32 data;
writel(MXS_CMD_I2C_SELECT, i2c->regs + MXS_I2C_QUEUECMD);
data = (addr << 1) | I2C_SMBUS_READ;
writel(data, i2c->regs + MXS_I2C_DATA);
data = MXS_CMD_I2C_READ | MXS_I2C_CTRL0_XFER_COUNT(len) | flags;
writel(data, i2c->regs + MXS_I2C_QUEUECMD);
}
static void mxs_i2c_pioq_setup_write(struct mxs_i2c_dev *i2c,
u8 addr, u8 *buf, int len, int flags)
{
u32 data;
int i, shifts_left;
data = MXS_CMD_I2C_WRITE | MXS_I2C_CTRL0_XFER_COUNT(len + 1) | flags;
writel(data, i2c->regs + MXS_I2C_QUEUECMD);
/*
* We have to copy the slave address (u8) and buffer (arbitrary number
* of u8) into the data register (u32). To achieve that, the u8 are put
* into the MSBs of 'data' which is then shifted for the next u8. When
* appropriate, 'data' is written to MXS_I2C_DATA. So, the first u32
* looks like this:
*
* 3 2 1 0
* 10987654|32109876|54321098|76543210
* --------+--------+--------+--------
* buffer+2|buffer+1|buffer+0|slave_addr
*/
data = ((addr << 1) | I2C_SMBUS_WRITE) << 24;
for (i = 0; i < len; i++) {
data >>= 8;
data |= buf[i] << 24;
if ((i & 3) == 2)
writel(data, i2c->regs + MXS_I2C_DATA);
}
/* Write out the remaining bytes if any */
shifts_left = 24 - (i & 3) * 8;
if (shifts_left)
writel(data >> shifts_left, i2c->regs + MXS_I2C_DATA);
}
/*
* TODO: should be replaceable with a waitqueue and RD_QUEUE_IRQ (setting the
* rd_threshold to 1). Couldn't get this to work, though.
*/
static int mxs_i2c_wait_for_data(struct mxs_i2c_dev *i2c)
{
unsigned long timeout = jiffies + msecs_to_jiffies(1000);
while (readl(i2c->regs + MXS_I2C_QUEUESTAT)
& MXS_I2C_QUEUESTAT_RD_QUEUE_EMPTY) {
if (time_after(jiffies, timeout))
return -ETIMEDOUT;
cond_resched();
}
return 0;
}
static int mxs_i2c_finish_read(struct mxs_i2c_dev *i2c, u8 *buf, int len)
{
u32 data;
int i;
for (i = 0; i < len; i++) {
if ((i & 3) == 0) {
if (mxs_i2c_wait_for_data(i2c))
return -ETIMEDOUT;
data = readl(i2c->regs + MXS_I2C_QUEUEDATA);
}
buf[i] = data & 0xff;
data >>= 8;
}
return 0;
}
/*
* Low level master read/write transaction.
*/
static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
int stop)
{
struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
int ret;
int flags;
dev_dbg(i2c->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
msg->addr, msg->len, msg->flags, stop);
if (msg->len == 0)
return -EINVAL;
init_completion(&i2c->cmd_complete);
flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;
if (msg->flags & I2C_M_RD)
mxs_i2c_pioq_setup_read(i2c, msg->addr, msg->len, flags);
else
mxs_i2c_pioq_setup_write(i2c, msg->addr, msg->buf, msg->len,
flags);
writel(MXS_I2C_QUEUECTRL_QUEUE_RUN,
i2c->regs + MXS_I2C_QUEUECTRL_SET);
ret = wait_for_completion_timeout(&i2c->cmd_complete,
msecs_to_jiffies(1000));
if (ret == 0)
goto timeout;
if ((!i2c->cmd_err) && (msg->flags & I2C_M_RD)) {
ret = mxs_i2c_finish_read(i2c, msg->buf, msg->len);
if (ret)
goto timeout;
}
if (i2c->cmd_err == -ENXIO)
mxs_i2c_reset(i2c);
dev_dbg(i2c->dev, "Done with err=%d\n", i2c->cmd_err);
return i2c->cmd_err;
timeout:
dev_dbg(i2c->dev, "Timeout!\n");
mxs_i2c_reset(i2c);
return -ETIMEDOUT;
}
static int mxs_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
int num)
{
int i;
int err;
for (i = 0; i < num; i++) {
err = mxs_i2c_xfer_msg(adap, &msgs[i], i == (num - 1));
if (err)
return err;
}
return num;
}
static u32 mxs_i2c_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
}
static irqreturn_t mxs_i2c_isr(int this_irq, void *dev_id)
{
struct mxs_i2c_dev *i2c = dev_id;
u32 stat = readl(i2c->regs + MXS_I2C_CTRL1) & MXS_I2C_IRQ_MASK;
bool is_last_cmd;
if (!stat)
return IRQ_NONE;
if (stat & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
i2c->cmd_err = -ENXIO;
else if (stat & (MXS_I2C_CTRL1_EARLY_TERM_IRQ |
MXS_I2C_CTRL1_MASTER_LOSS_IRQ |
MXS_I2C_CTRL1_SLAVE_STOP_IRQ | MXS_I2C_CTRL1_SLAVE_IRQ))
/* MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ is only for slaves */
i2c->cmd_err = -EIO;
else
i2c->cmd_err = 0;
is_last_cmd = (readl(i2c->regs + MXS_I2C_QUEUESTAT) &
MXS_I2C_QUEUESTAT_WRITE_QUEUE_CNT_MASK) == 0;
if (is_last_cmd || i2c->cmd_err)
complete(&i2c->cmd_complete);
writel(stat, i2c->regs + MXS_I2C_CTRL1_CLR);
return IRQ_HANDLED;
}
static const struct i2c_algorithm mxs_i2c_algo = {
.master_xfer = mxs_i2c_xfer,
.functionality = mxs_i2c_func,
};
static int __devinit mxs_i2c_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct mxs_i2c_dev *i2c;
struct i2c_adapter *adap;
struct resource *res;
resource_size_t res_size;
int err, irq;
i2c = devm_kzalloc(dev, sizeof(struct mxs_i2c_dev), GFP_KERNEL);
if (!i2c)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENOENT;
res_size = resource_size(res);
if (!devm_request_mem_region(dev, res->start, res_size, res->name))
return -EBUSY;
i2c->regs = devm_ioremap_nocache(dev, res->start, res_size);
if (!i2c->regs)
return -EBUSY;
irq = platform_get_irq(pdev, 0);
if (irq < 0)
return irq;
err = devm_request_irq(dev, irq, mxs_i2c_isr, 0, dev_name(dev), i2c);
if (err)
return err;
i2c->dev = dev;
platform_set_drvdata(pdev, i2c);
/* Do reset to enforce correct startup after pinmuxing */
mxs_i2c_reset(i2c);
adap = &i2c->adapter;
strlcpy(adap->name, "MXS I2C adapter", sizeof(adap->name));
adap->owner = THIS_MODULE;
adap->algo = &mxs_i2c_algo;
adap->dev.parent = dev;
adap->nr = pdev->id;
i2c_set_adapdata(adap, i2c);
err = i2c_add_numbered_adapter(adap);
if (err) {
dev_err(dev, "Failed to add adapter (%d)\n", err);
writel(MXS_I2C_CTRL0_SFTRST,
i2c->regs + MXS_I2C_CTRL0_SET);
return err;
}
return 0;
}
static int __devexit mxs_i2c_remove(struct platform_device *pdev)
{
struct mxs_i2c_dev *i2c = platform_get_drvdata(pdev);
int ret;
ret = i2c_del_adapter(&i2c->adapter);
if (ret)
return -EBUSY;
writel(MXS_I2C_QUEUECTRL_QUEUE_RUN,
i2c->regs + MXS_I2C_QUEUECTRL_CLR);
writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET);
platform_set_drvdata(pdev, NULL);
return 0;
}
static struct platform_driver mxs_i2c_driver = {
.driver = {
.name = DRIVER_NAME,
.owner = THIS_MODULE,
},
.remove = __devexit_p(mxs_i2c_remove),
};
static int __init mxs_i2c_init(void)
{
return platform_driver_probe(&mxs_i2c_driver, mxs_i2c_probe);
}
subsys_initcall(mxs_i2c_init);
static void __exit mxs_i2c_exit(void)
{
platform_driver_unregister(&mxs_i2c_driver);
}
module_exit(mxs_i2c_exit);
MODULE_AUTHOR("Wolfram Sang <w.sang@pengutronix.de>");
MODULE_DESCRIPTION("MXS I2C Bus Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRIVER_NAME);