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linux-next/drivers/i2c/busses/i2c-bcm2835.c
Florian Meier 07a27a0047 i2c: bcm2835: Linking platform nodes to adapter nodes 
In order to find I2C devices in the device tree, the platform nodes
have to be known by the I2C core. This requires setting the
dev.of_node parameter of the adapter.

Signed-off-by: Florian Meier <florian.meier@koalo.de>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2013-11-28 09:47:53 +01:00

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/*
* BCM2835 master mode driver
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* 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/completion.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#define BCM2835_I2C_C 0x0
#define BCM2835_I2C_S 0x4
#define BCM2835_I2C_DLEN 0x8
#define BCM2835_I2C_A 0xc
#define BCM2835_I2C_FIFO 0x10
#define BCM2835_I2C_DIV 0x14
#define BCM2835_I2C_DEL 0x18
#define BCM2835_I2C_CLKT 0x1c
#define BCM2835_I2C_C_READ BIT(0)
#define BCM2835_I2C_C_CLEAR BIT(4) /* bits 4 and 5 both clear */
#define BCM2835_I2C_C_ST BIT(7)
#define BCM2835_I2C_C_INTD BIT(8)
#define BCM2835_I2C_C_INTT BIT(9)
#define BCM2835_I2C_C_INTR BIT(10)
#define BCM2835_I2C_C_I2CEN BIT(15)
#define BCM2835_I2C_S_TA BIT(0)
#define BCM2835_I2C_S_DONE BIT(1)
#define BCM2835_I2C_S_TXW BIT(2)
#define BCM2835_I2C_S_RXR BIT(3)
#define BCM2835_I2C_S_TXD BIT(4)
#define BCM2835_I2C_S_RXD BIT(5)
#define BCM2835_I2C_S_TXE BIT(6)
#define BCM2835_I2C_S_RXF BIT(7)
#define BCM2835_I2C_S_ERR BIT(8)
#define BCM2835_I2C_S_CLKT BIT(9)
#define BCM2835_I2C_S_LEN BIT(10) /* Fake bit for SW error reporting */
#define BCM2835_I2C_TIMEOUT (msecs_to_jiffies(1000))
struct bcm2835_i2c_dev {
struct device *dev;
void __iomem *regs;
struct clk *clk;
int irq;
struct i2c_adapter adapter;
struct completion completion;
u32 msg_err;
u8 *msg_buf;
size_t msg_buf_remaining;
};
static inline void bcm2835_i2c_writel(struct bcm2835_i2c_dev *i2c_dev,
u32 reg, u32 val)
{
writel(val, i2c_dev->regs + reg);
}
static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg)
{
return readl(i2c_dev->regs + reg);
}
static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev)
{
u32 val;
while (i2c_dev->msg_buf_remaining) {
val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
if (!(val & BCM2835_I2C_S_TXD))
break;
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_FIFO,
*i2c_dev->msg_buf);
i2c_dev->msg_buf++;
i2c_dev->msg_buf_remaining--;
}
}
static void bcm2835_drain_rxfifo(struct bcm2835_i2c_dev *i2c_dev)
{
u32 val;
while (i2c_dev->msg_buf_remaining) {
val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
if (!(val & BCM2835_I2C_S_RXD))
break;
*i2c_dev->msg_buf = bcm2835_i2c_readl(i2c_dev,
BCM2835_I2C_FIFO);
i2c_dev->msg_buf++;
i2c_dev->msg_buf_remaining--;
}
}
static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data)
{
struct bcm2835_i2c_dev *i2c_dev = data;
u32 val, err;
val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, val);
err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR);
if (err) {
i2c_dev->msg_err = err;
complete(&i2c_dev->completion);
return IRQ_HANDLED;
}
if (val & BCM2835_I2C_S_RXD) {
bcm2835_drain_rxfifo(i2c_dev);
if (!(val & BCM2835_I2C_S_DONE))
return IRQ_HANDLED;
}
if (val & BCM2835_I2C_S_DONE) {
if (i2c_dev->msg_buf_remaining)
i2c_dev->msg_err = BCM2835_I2C_S_LEN;
else
i2c_dev->msg_err = 0;
complete(&i2c_dev->completion);
return IRQ_HANDLED;
}
if (val & BCM2835_I2C_S_TXD) {
bcm2835_fill_txfifo(i2c_dev);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
static int bcm2835_i2c_xfer_msg(struct bcm2835_i2c_dev *i2c_dev,
struct i2c_msg *msg)
{
u32 c;
int time_left;
i2c_dev->msg_buf = msg->buf;
i2c_dev->msg_buf_remaining = msg->len;
reinit_completion(&i2c_dev->completion);
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR);
if (msg->flags & I2C_M_RD) {
c = BCM2835_I2C_C_READ | BCM2835_I2C_C_INTR;
} else {
c = BCM2835_I2C_C_INTT;
bcm2835_fill_txfifo(i2c_dev);
}
c |= BCM2835_I2C_C_ST | BCM2835_I2C_C_INTD | BCM2835_I2C_C_I2CEN;
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_A, msg->addr);
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DLEN, msg->len);
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, c);
time_left = wait_for_completion_timeout(&i2c_dev->completion,
BCM2835_I2C_TIMEOUT);
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR);
if (!time_left) {
dev_err(i2c_dev->dev, "i2c transfer timed out\n");
return -ETIMEDOUT;
}
if (likely(!i2c_dev->msg_err))
return 0;
if ((i2c_dev->msg_err & BCM2835_I2C_S_ERR) &&
(msg->flags & I2C_M_IGNORE_NAK))
return 0;
dev_err(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err);
if (i2c_dev->msg_err & BCM2835_I2C_S_ERR)
return -EREMOTEIO;
else
return -EIO;
}
static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
int num)
{
struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
int i;
int ret = 0;
for (i = 0; i < num; i++) {
ret = bcm2835_i2c_xfer_msg(i2c_dev, &msgs[i]);
if (ret)
break;
}
return ret ?: i;
}
static u32 bcm2835_i2c_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static const struct i2c_algorithm bcm2835_i2c_algo = {
.master_xfer = bcm2835_i2c_xfer,
.functionality = bcm2835_i2c_func,
};
static int bcm2835_i2c_probe(struct platform_device *pdev)
{
struct bcm2835_i2c_dev *i2c_dev;
struct resource *mem, *requested, *irq;
u32 bus_clk_rate, divider;
int ret;
struct i2c_adapter *adap;
i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
if (!i2c_dev) {
dev_err(&pdev->dev, "Cannot allocate i2c_dev\n");
return -ENOMEM;
}
platform_set_drvdata(pdev, i2c_dev);
i2c_dev->dev = &pdev->dev;
init_completion(&i2c_dev->completion);
mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!mem) {
dev_err(&pdev->dev, "No mem resource\n");
return -ENODEV;
}
requested = devm_request_mem_region(&pdev->dev, mem->start,
resource_size(mem),
dev_name(&pdev->dev));
if (!requested) {
dev_err(&pdev->dev, "Could not claim register region\n");
return -EBUSY;
}
i2c_dev->regs = devm_ioremap(&pdev->dev, mem->start,
resource_size(mem));
if (!i2c_dev->regs) {
dev_err(&pdev->dev, "Could not map registers\n");
return -ENOMEM;
}
i2c_dev->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(i2c_dev->clk)) {
dev_err(&pdev->dev, "Could not get clock\n");
return PTR_ERR(i2c_dev->clk);
}
ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
&bus_clk_rate);
if (ret < 0) {
dev_warn(&pdev->dev,
"Could not read clock-frequency property\n");
bus_clk_rate = 100000;
}
divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), bus_clk_rate);
/*
* Per the datasheet, the register is always interpreted as an even
* number, by rounding down. In other words, the LSB is ignored. So,
* if the LSB is set, increment the divider to avoid any issue.
*/
if (divider & 1)
divider++;
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider);
irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
if (!irq) {
dev_err(&pdev->dev, "No IRQ resource\n");
return -ENODEV;
}
i2c_dev->irq = irq->start;
ret = request_irq(i2c_dev->irq, bcm2835_i2c_isr, IRQF_SHARED,
dev_name(&pdev->dev), i2c_dev);
if (ret) {
dev_err(&pdev->dev, "Could not request IRQ\n");
return -ENODEV;
}
adap = &i2c_dev->adapter;
i2c_set_adapdata(adap, i2c_dev);
adap->owner = THIS_MODULE;
adap->class = I2C_CLASS_HWMON;
strlcpy(adap->name, "bcm2835 I2C adapter", sizeof(adap->name));
adap->algo = &bcm2835_i2c_algo;
adap->dev.parent = &pdev->dev;
adap->dev.of_node = pdev->dev.of_node;
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0);
ret = i2c_add_adapter(adap);
if (ret)
free_irq(i2c_dev->irq, i2c_dev);
return ret;
}
static int bcm2835_i2c_remove(struct platform_device *pdev)
{
struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
free_irq(i2c_dev->irq, i2c_dev);
i2c_del_adapter(&i2c_dev->adapter);
return 0;
}
static const struct of_device_id bcm2835_i2c_of_match[] = {
{ .compatible = "brcm,bcm2835-i2c" },
{},
};
MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match);
static struct platform_driver bcm2835_i2c_driver = {
.probe = bcm2835_i2c_probe,
.remove = bcm2835_i2c_remove,
.driver = {
.name = "i2c-bcm2835",
.owner = THIS_MODULE,
.of_match_table = bcm2835_i2c_of_match,
},
};
module_platform_driver(bcm2835_i2c_driver);
MODULE_AUTHOR("Stephen Warren <swarren@wwwdotorg.org>");
MODULE_DESCRIPTION("BCM2835 I2C bus adapter");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:i2c-bcm2835");
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