linux/drivers/i2c/busses/i2c-gpio.c
Hamish Martin 3747cd2efe i2c: gpio: suppress error on probe defer
If a GPIO we are trying to use is not available and we are deferring
the probe, don't output an error message.
This seems to have been the intent of commit 05c7477885
("i2c: gpio: Add support for named gpios in DT") but the error was
still output due to not checking the updated 'retdesc'.

Fixes: 05c7477885 ("i2c: gpio: Add support for named gpios in DT")
Signed-off-by: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2020-03-10 12:31:55 +01:00

525 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Bitbanging I2C bus driver using the GPIO API
*
* Copyright (C) 2007 Atmel Corporation
*/
#include <linux/completion.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c-algo-bit.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_data/i2c-gpio.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
struct i2c_gpio_private_data {
struct gpio_desc *sda;
struct gpio_desc *scl;
struct i2c_adapter adap;
struct i2c_algo_bit_data bit_data;
struct i2c_gpio_platform_data pdata;
#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
struct dentry *debug_dir;
/* these must be protected by bus lock */
struct completion scl_irq_completion;
u64 scl_irq_data;
#endif
};
/*
* Toggle SDA by changing the output value of the pin. This is only
* valid for pins configured as open drain (i.e. setting the value
* high effectively turns off the output driver.)
*/
static void i2c_gpio_setsda_val(void *data, int state)
{
struct i2c_gpio_private_data *priv = data;
gpiod_set_value_cansleep(priv->sda, state);
}
/*
* Toggle SCL by changing the output value of the pin. This is used
* for pins that are configured as open drain and for output-only
* pins. The latter case will break the i2c protocol, but it will
* often work in practice.
*/
static void i2c_gpio_setscl_val(void *data, int state)
{
struct i2c_gpio_private_data *priv = data;
gpiod_set_value_cansleep(priv->scl, state);
}
static int i2c_gpio_getsda(void *data)
{
struct i2c_gpio_private_data *priv = data;
return gpiod_get_value_cansleep(priv->sda);
}
static int i2c_gpio_getscl(void *data)
{
struct i2c_gpio_private_data *priv = data;
return gpiod_get_value_cansleep(priv->scl);
}
#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
static struct dentry *i2c_gpio_debug_dir;
#define setsda(bd, val) ((bd)->setsda((bd)->data, val))
#define setscl(bd, val) ((bd)->setscl((bd)->data, val))
#define getsda(bd) ((bd)->getsda((bd)->data))
#define getscl(bd) ((bd)->getscl((bd)->data))
#define WIRE_ATTRIBUTE(wire) \
static int fops_##wire##_get(void *data, u64 *val) \
{ \
struct i2c_gpio_private_data *priv = data; \
\
i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
*val = get##wire(&priv->bit_data); \
i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
return 0; \
} \
static int fops_##wire##_set(void *data, u64 val) \
{ \
struct i2c_gpio_private_data *priv = data; \
\
i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
set##wire(&priv->bit_data, val); \
i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
return 0; \
} \
DEFINE_DEBUGFS_ATTRIBUTE(fops_##wire, fops_##wire##_get, fops_##wire##_set, "%llu\n")
WIRE_ATTRIBUTE(scl);
WIRE_ATTRIBUTE(sda);
static void i2c_gpio_incomplete_transfer(struct i2c_gpio_private_data *priv,
u32 pattern, u8 pattern_size)
{
struct i2c_algo_bit_data *bit_data = &priv->bit_data;
int i;
i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
/* START condition */
setsda(bit_data, 0);
udelay(bit_data->udelay);
/* Send pattern, request ACK, don't send STOP */
for (i = pattern_size - 1; i >= 0; i--) {
setscl(bit_data, 0);
udelay(bit_data->udelay / 2);
setsda(bit_data, (pattern >> i) & 1);
udelay((bit_data->udelay + 1) / 2);
setscl(bit_data, 1);
udelay(bit_data->udelay);
}
i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
}
static int fops_incomplete_addr_phase_set(void *data, u64 addr)
{
struct i2c_gpio_private_data *priv = data;
u32 pattern;
if (addr > 0x7f)
return -EINVAL;
/* ADDR (7 bit) + RD (1 bit) + Client ACK, keep SDA hi (1 bit) */
pattern = (addr << 2) | 3;
i2c_gpio_incomplete_transfer(priv, pattern, 9);
return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_addr_phase, NULL, fops_incomplete_addr_phase_set, "%llu\n");
static int fops_incomplete_write_byte_set(void *data, u64 addr)
{
struct i2c_gpio_private_data *priv = data;
u32 pattern;
if (addr > 0x7f)
return -EINVAL;
/* ADDR (7 bit) + WR (1 bit) + Client ACK (1 bit) */
pattern = (addr << 2) | 1;
/* 0x00 (8 bit) + Client ACK, keep SDA hi (1 bit) */
pattern = (pattern << 9) | 1;
i2c_gpio_incomplete_transfer(priv, pattern, 18);
return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_write_byte, NULL, fops_incomplete_write_byte_set, "%llu\n");
static int i2c_gpio_fi_act_on_scl_irq(struct i2c_gpio_private_data *priv,
irqreturn_t handler(int, void*))
{
int ret, irq = gpiod_to_irq(priv->scl);
if (irq < 0)
return irq;
i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
ret = gpiod_direction_input(priv->scl);
if (ret)
goto unlock;
reinit_completion(&priv->scl_irq_completion);
ret = request_irq(irq, handler, IRQF_TRIGGER_FALLING,
"i2c_gpio_fault_injector_scl_irq", priv);
if (ret)
goto output;
wait_for_completion_interruptible(&priv->scl_irq_completion);
free_irq(irq, priv);
output:
ret = gpiod_direction_output(priv->scl, 1) ?: ret;
unlock:
i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
return ret;
}
static irqreturn_t lose_arbitration_irq(int irq, void *dev_id)
{
struct i2c_gpio_private_data *priv = dev_id;
setsda(&priv->bit_data, 0);
udelay(priv->scl_irq_data);
setsda(&priv->bit_data, 1);
complete(&priv->scl_irq_completion);
return IRQ_HANDLED;
}
static int fops_lose_arbitration_set(void *data, u64 duration)
{
struct i2c_gpio_private_data *priv = data;
if (duration > 100 * 1000)
return -EINVAL;
priv->scl_irq_data = duration;
/*
* Interrupt on falling SCL. This ensures that the master under test has
* really started the transfer. Interrupt on falling SDA did only
* exercise 'bus busy' detection on some HW but not 'arbitration lost'.
* Note that the interrupt latency may cause the first bits to be
* transmitted correctly.
*/
return i2c_gpio_fi_act_on_scl_irq(priv, lose_arbitration_irq);
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_lose_arbitration, NULL, fops_lose_arbitration_set, "%llu\n");
static irqreturn_t inject_panic_irq(int irq, void *dev_id)
{
struct i2c_gpio_private_data *priv = dev_id;
udelay(priv->scl_irq_data);
panic("I2C fault injector induced panic");
return IRQ_HANDLED;
}
static int fops_inject_panic_set(void *data, u64 duration)
{
struct i2c_gpio_private_data *priv = data;
if (duration > 100 * 1000)
return -EINVAL;
priv->scl_irq_data = duration;
/*
* Interrupt on falling SCL. This ensures that the master under test has
* really started the transfer.
*/
return i2c_gpio_fi_act_on_scl_irq(priv, inject_panic_irq);
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_inject_panic, NULL, fops_inject_panic_set, "%llu\n");
static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
{
struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
/*
* If there will be a debugfs-dir per i2c adapter somewhen, put the
* 'fault-injector' dir there. Until then, we have a global dir with
* all adapters as subdirs.
*/
if (!i2c_gpio_debug_dir) {
i2c_gpio_debug_dir = debugfs_create_dir("i2c-fault-injector", NULL);
if (!i2c_gpio_debug_dir)
return;
}
priv->debug_dir = debugfs_create_dir(pdev->name, i2c_gpio_debug_dir);
if (!priv->debug_dir)
return;
init_completion(&priv->scl_irq_completion);
debugfs_create_file_unsafe("incomplete_address_phase", 0200, priv->debug_dir,
priv, &fops_incomplete_addr_phase);
debugfs_create_file_unsafe("incomplete_write_byte", 0200, priv->debug_dir,
priv, &fops_incomplete_write_byte);
if (priv->bit_data.getscl) {
debugfs_create_file_unsafe("inject_panic", 0200, priv->debug_dir,
priv, &fops_inject_panic);
debugfs_create_file_unsafe("lose_arbitration", 0200, priv->debug_dir,
priv, &fops_lose_arbitration);
}
debugfs_create_file_unsafe("scl", 0600, priv->debug_dir, priv, &fops_scl);
debugfs_create_file_unsafe("sda", 0600, priv->debug_dir, priv, &fops_sda);
}
static void i2c_gpio_fault_injector_exit(struct platform_device *pdev)
{
struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
debugfs_remove_recursive(priv->debug_dir);
}
#else
static inline void i2c_gpio_fault_injector_init(struct platform_device *pdev) {}
static inline void i2c_gpio_fault_injector_exit(struct platform_device *pdev) {}
#endif /* CONFIG_I2C_GPIO_FAULT_INJECTOR*/
static void of_i2c_gpio_get_props(struct device_node *np,
struct i2c_gpio_platform_data *pdata)
{
u32 reg;
of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay);
if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", &reg))
pdata->timeout = msecs_to_jiffies(reg);
pdata->sda_is_open_drain =
of_property_read_bool(np, "i2c-gpio,sda-open-drain");
pdata->scl_is_open_drain =
of_property_read_bool(np, "i2c-gpio,scl-open-drain");
pdata->scl_is_output_only =
of_property_read_bool(np, "i2c-gpio,scl-output-only");
}
static struct gpio_desc *i2c_gpio_get_desc(struct device *dev,
const char *con_id,
unsigned int index,
enum gpiod_flags gflags)
{
struct gpio_desc *retdesc;
int ret;
retdesc = devm_gpiod_get(dev, con_id, gflags);
if (!IS_ERR(retdesc)) {
dev_dbg(dev, "got GPIO from name %s\n", con_id);
return retdesc;
}
retdesc = devm_gpiod_get_index(dev, NULL, index, gflags);
if (!IS_ERR(retdesc)) {
dev_dbg(dev, "got GPIO from index %u\n", index);
return retdesc;
}
ret = PTR_ERR(retdesc);
/* FIXME: hack in the old code, is this really necessary? */
if (ret == -EINVAL)
retdesc = ERR_PTR(-EPROBE_DEFER);
/* This happens if the GPIO driver is not yet probed, let's defer */
if (ret == -ENOENT)
retdesc = ERR_PTR(-EPROBE_DEFER);
if (PTR_ERR(retdesc) != -EPROBE_DEFER)
dev_err(dev, "error trying to get descriptor: %d\n", ret);
return retdesc;
}
static int i2c_gpio_probe(struct platform_device *pdev)
{
struct i2c_gpio_private_data *priv;
struct i2c_gpio_platform_data *pdata;
struct i2c_algo_bit_data *bit_data;
struct i2c_adapter *adap;
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
enum gpiod_flags gflags;
int ret;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
adap = &priv->adap;
bit_data = &priv->bit_data;
pdata = &priv->pdata;
if (np) {
of_i2c_gpio_get_props(np, pdata);
} else {
/*
* If all platform data settings are zero it is OK
* to not provide any platform data from the board.
*/
if (dev_get_platdata(dev))
memcpy(pdata, dev_get_platdata(dev), sizeof(*pdata));
}
/*
* First get the GPIO pins; if it fails, we'll defer the probe.
* If the SCL/SDA lines are marked "open drain" by platform data or
* device tree then this means that something outside of our control is
* marking these lines to be handled as open drain, and we should just
* handle them as we handle any other output. Else we enforce open
* drain as this is required for an I2C bus.
*/
if (pdata->sda_is_open_drain)
gflags = GPIOD_OUT_HIGH;
else
gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
priv->sda = i2c_gpio_get_desc(dev, "sda", 0, gflags);
if (IS_ERR(priv->sda))
return PTR_ERR(priv->sda);
if (pdata->scl_is_open_drain)
gflags = GPIOD_OUT_HIGH;
else
gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
priv->scl = i2c_gpio_get_desc(dev, "scl", 1, gflags);
if (IS_ERR(priv->scl))
return PTR_ERR(priv->scl);
if (gpiod_cansleep(priv->sda) || gpiod_cansleep(priv->scl))
dev_warn(dev, "Slow GPIO pins might wreak havoc into I2C/SMBus bus timing");
else
bit_data->can_do_atomic = true;
bit_data->setsda = i2c_gpio_setsda_val;
bit_data->setscl = i2c_gpio_setscl_val;
if (!pdata->scl_is_output_only)
bit_data->getscl = i2c_gpio_getscl;
bit_data->getsda = i2c_gpio_getsda;
if (pdata->udelay)
bit_data->udelay = pdata->udelay;
else if (pdata->scl_is_output_only)
bit_data->udelay = 50; /* 10 kHz */
else
bit_data->udelay = 5; /* 100 kHz */
if (pdata->timeout)
bit_data->timeout = pdata->timeout;
else
bit_data->timeout = HZ / 10; /* 100 ms */
bit_data->data = priv;
adap->owner = THIS_MODULE;
if (np)
strlcpy(adap->name, dev_name(dev), sizeof(adap->name));
else
snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
adap->algo_data = bit_data;
adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
adap->dev.parent = dev;
adap->dev.of_node = np;
adap->nr = pdev->id;
ret = i2c_bit_add_numbered_bus(adap);
if (ret)
return ret;
platform_set_drvdata(pdev, priv);
/*
* FIXME: using global GPIO numbers is not helpful. If/when we
* get accessors to get the actual name of the GPIO line,
* from the descriptor, then provide that instead.
*/
dev_info(dev, "using lines %u (SDA) and %u (SCL%s)\n",
desc_to_gpio(priv->sda), desc_to_gpio(priv->scl),
pdata->scl_is_output_only
? ", no clock stretching" : "");
i2c_gpio_fault_injector_init(pdev);
return 0;
}
static int i2c_gpio_remove(struct platform_device *pdev)
{
struct i2c_gpio_private_data *priv;
struct i2c_adapter *adap;
i2c_gpio_fault_injector_exit(pdev);
priv = platform_get_drvdata(pdev);
adap = &priv->adap;
i2c_del_adapter(adap);
return 0;
}
#if defined(CONFIG_OF)
static const struct of_device_id i2c_gpio_dt_ids[] = {
{ .compatible = "i2c-gpio", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);
#endif
static struct platform_driver i2c_gpio_driver = {
.driver = {
.name = "i2c-gpio",
.of_match_table = of_match_ptr(i2c_gpio_dt_ids),
},
.probe = i2c_gpio_probe,
.remove = i2c_gpio_remove,
};
static int __init i2c_gpio_init(void)
{
int ret;
ret = platform_driver_register(&i2c_gpio_driver);
if (ret)
printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);
return ret;
}
subsys_initcall(i2c_gpio_init);
static void __exit i2c_gpio_exit(void)
{
platform_driver_unregister(&i2c_gpio_driver);
}
module_exit(i2c_gpio_exit);
MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:i2c-gpio");