Release 4.11 drivers/i2c/busses/i2c-bcm2835.c
/*
* 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_CDIV_MIN 0x0002
#define BCM2835_I2C_CDIV_MAX 0xFFFE
struct bcm2835_i2c_dev {
struct device *dev;
void __iomem *regs;
struct clk *clk;
int irq;
u32 bus_clk_rate;
struct i2c_adapter adapter;
struct completion completion;
struct i2c_msg *curr_msg;
int num_msgs;
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);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Stephen Warren | 29 | 100.00% | 1 | 100.00% |
| Total | 29 | 100.00% | 1 | 100.00% |
static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg)
{
return readl(i2c_dev->regs + reg);
}
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| Person | Tokens | Prop | Commits | CommitProp |
| Stephen Warren | 25 | 100.00% | 1 | 100.00% |
| Total | 25 | 100.00% | 1 | 100.00% |
static int bcm2835_i2c_set_divider(struct bcm2835_i2c_dev *i2c_dev)
{
u32 divider;
divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk),
i2c_dev->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++;
if ((divider < BCM2835_I2C_CDIV_MIN) ||
(divider > BCM2835_I2C_CDIV_MAX)) {
dev_err_ratelimited(i2c_dev->dev, "Invalid clock-frequency\n");
return -EINVAL;
}
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider);
return 0;
}
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| Person | Tokens | Prop | Commits | CommitProp |
| Noralf Trönnes | 81 | 100.00% | 1 | 100.00% |
| Total | 81 | 100.00% | 1 | 100.00% |
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--;
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Stephen Warren | 63 | 100.00% | 1 | 100.00% |
| Total | 63 | 100.00% | 1 | 100.00% |
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--;
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Stephen Warren | 63 | 100.00% | 1 | 100.00% |
| Total | 63 | 100.00% | 1 | 100.00% |
/*
* Repeated Start Condition (Sr)
* The BCM2835 ARM Peripherals datasheet mentions a way to trigger a Sr when it
* talks about reading from a slave with 10 bit address. This is achieved by
* issuing a write, poll the I2CS.TA flag and wait for it to be set, and then
* issue a read.
* A comment in https://github.com/raspberrypi/linux/issues/254 shows how the
* firmware actually does it using polling and says that it's a workaround for
* a problem in the state machine.
* It turns out that it is possible to use the TXW interrupt to know when the
* transfer is active, provided the FIFO has not been prefilled.
*/
static void bcm2835_i2c_start_transfer(struct bcm2835_i2c_dev *i2c_dev)
{
u32 c = BCM2835_I2C_C_ST | BCM2835_I2C_C_I2CEN;
struct i2c_msg *msg = i2c_dev->curr_msg;
bool last_msg = (i2c_dev->num_msgs == 1);
if (!i2c_dev->num_msgs)
return;
i2c_dev->num_msgs--;
i2c_dev->msg_buf = msg->buf;
i2c_dev->msg_buf_remaining = msg->len;
if (msg->flags & I2C_M_RD)
c |= BCM2835_I2C_C_READ | BCM2835_I2C_C_INTR;
else
c |= BCM2835_I2C_C_INTT;
if (last_msg)
c |= BCM2835_I2C_C_INTD;
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);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Noralf Trönnes | 125 | 100.00% | 1 | 100.00% |
| Total | 125 | 100.00% | 1 | 100.00% |
/*
* Note about I2C_C_CLEAR on error:
* The I2C_C_CLEAR on errors will take some time to resolve -- if you were in
* non-idle state and I2C_C_READ, it sets an abort_rx flag and runs through
* the state machine to send a NACK and a STOP. Since we're setting CLEAR
* without I2CEN, that NACK will be hanging around queued up for next time
* we start the engine.
*/
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);
err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR);
if (err) {
i2c_dev->msg_err = err;
goto complete;
}
if (val & BCM2835_I2C_S_DONE) {
if (!i2c_dev->curr_msg) {
dev_err(i2c_dev->dev, "Got unexpected interrupt (from firmware?)\n");
} else if (i2c_dev->curr_msg->flags & I2C_M_RD) {
bcm2835_drain_rxfifo(i2c_dev);
val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
}
if ((val & BCM2835_I2C_S_RXD) || i2c_dev->msg_buf_remaining)
i2c_dev->msg_err = BCM2835_I2C_S_LEN;
else
i2c_dev->msg_err = 0;
goto complete;
}
if (val & BCM2835_I2C_S_TXW) {
if (!i2c_dev->msg_buf_remaining) {
i2c_dev->msg_err = val | BCM2835_I2C_S_LEN;
goto complete;
}
bcm2835_fill_txfifo(i2c_dev);
if (i2c_dev->num_msgs && !i2c_dev->msg_buf_remaining) {
i2c_dev->curr_msg++;
bcm2835_i2c_start_transfer(i2c_dev);
}
return IRQ_HANDLED;
}
if (val & BCM2835_I2C_S_RXR) {
if (!i2c_dev->msg_buf_remaining) {
i2c_dev->msg_err = val | BCM2835_I2C_S_LEN;
goto complete;
}
bcm2835_drain_rxfifo(i2c_dev);
return IRQ_HANDLED;
}
return IRQ_NONE;
complete:
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR);
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, BCM2835_I2C_S_CLKT |
BCM2835_I2C_S_ERR | BCM2835_I2C_S_DONE);
complete(&i2c_dev->completion);
return IRQ_HANDLED;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Noralf Trönnes | 143 | 52.38% | 3 | 60.00% |
| Stephen Warren | 111 | 40.66% | 1 | 20.00% |
| Stefan Wahren | 19 | 6.96% | 1 | 20.00% |
| Total | 273 | 100.00% | 5 | 100.00% |
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);
unsigned long time_left;
int i, ret;
for (i = 0; i < (num - 1); i++)
if (msgs[i].flags & I2C_M_RD) {
dev_warn_once(i2c_dev->dev,
"only one read message supported, has to be last\n");
return -EOPNOTSUPP;
}
ret = bcm2835_i2c_set_divider(i2c_dev);
if (ret)
return ret;
i2c_dev->curr_msg = msgs;
i2c_dev->num_msgs = num;
reinit_completion(&i2c_dev->completion);
bcm2835_i2c_start_transfer(i2c_dev);
time_left = wait_for_completion_timeout(&i2c_dev->completion,
adap->timeout);
if (!time_left) {
bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C,
BCM2835_I2C_C_CLEAR);
dev_err(i2c_dev->dev, "i2c transfer timed out\n");
return -ETIMEDOUT;
}
if (!i2c_dev->msg_err)
return num;
dev_dbg(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err);
if (i2c_dev->msg_err & BCM2835_I2C_S_ERR)
return -EREMOTEIO;
return -EIO;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Stephen Warren | 111 | 54.95% | 1 | 14.29% |
| Noralf Trönnes | 89 | 44.06% | 5 | 71.43% |
| Nicholas Mc Guire | 2 | 0.99% | 1 | 14.29% |
| Total | 202 | 100.00% | 7 | 100.00% |
static u32 bcm2835_i2c_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Stephen Warren | 16 | 100.00% | 1 | 100.00% |
| Total | 16 | 100.00% | 1 | 100.00% |
static const struct i2c_algorithm bcm2835_i2c_algo = {
.master_xfer = bcm2835_i2c_xfer,
.functionality = bcm2835_i2c_func,
};
/*
* This HW was reported to have problems with clock stretching:
* http://www.advamation.com/knowhow/raspberrypi/rpi-i2c-bug.html
* https://www.raspberrypi.org/forums/viewtopic.php?p=146272
*/
static const struct i2c_adapter_quirks bcm2835_i2c_quirks = {
.flags = I2C_AQ_NO_CLK_STRETCH,
};
static int bcm2835_i2c_probe(struct platform_device *pdev)
{
struct bcm2835_i2c_dev *i2c_dev;
struct resource *mem, *irq;
int ret;
struct i2c_adapter *adap;
i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
if (!i2c_dev)
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);
i2c_dev->regs = devm_ioremap_resource(&pdev->dev, mem);
if (IS_ERR(i2c_dev->regs))
return PTR_ERR(i2c_dev->regs);
i2c_dev->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(i2c_dev->clk)) {
if (PTR_ERR(i2c_dev->clk) != -EPROBE_DEFER)
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",
&i2c_dev->bus_clk_rate);
if (ret < 0) {
dev_warn(&pdev->dev,
"Could not read clock-frequency property\n");
i2c_dev->bus_clk_rate = 100000;
}
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_DEPRECATED;
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;
adap->quirks = &bcm2835_i2c_quirks;
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;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Stephen Warren | 370 | 88.94% | 1 | 12.50% |
| Eric Anholt | 12 | 2.88% | 1 | 12.50% |
| Florian Meier | 12 | 2.88% | 1 | 12.50% |
| Jingoo Han | 8 | 1.92% | 1 | 12.50% |
| Nicola Corna | 7 | 1.68% | 1 | 12.50% |
| Noralf Trönnes | 4 | 0.96% | 1 | 12.50% |
| Silvan Wicki | 2 | 0.48% | 1 | 12.50% |
| Wolfram Sang | 1 | 0.24% | 1 | 12.50% |
| Total | 416 | 100.00% | 8 | 100.00% |
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;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Stephen Warren | 41 | 100.00% | 1 | 100.00% |
| Total | 41 | 100.00% | 1 | 100.00% |
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",
.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");
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Stephen Warren | 1104 | 67.15% | 1 | 6.67% |
| Noralf Trönnes | 455 | 27.68% | 6 | 40.00% |
| Nicola Corna | 21 | 1.28% | 1 | 6.67% |
| Stefan Wahren | 19 | 1.16% | 1 | 6.67% |
| Eric Anholt | 12 | 0.73% | 1 | 6.67% |
| Florian Meier | 12 | 0.73% | 1 | 6.67% |
| Silvan Wicki | 10 | 0.61% | 1 | 6.67% |
| Jingoo Han | 8 | 0.49% | 1 | 6.67% |
| Nicholas Mc Guire | 2 | 0.12% | 1 | 6.67% |
| Wolfram Sang | 1 | 0.06% | 1 | 6.67% |
| Total | 1644 | 100.00% | 15 | 100.00% |
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