GPIOs may not be available immediately when i2c-gpio looks for them.
Implement support for deferred probing so that probing can be
attempted again later when GPIO pins are finally available.
Signed-off-by: Jean Delvare <khali@xxxxxxxxxxxx>
Cc: Haavard Skinnemoen <hskinnemoen@xxxxxxxxx>
---
A little more changes were needed than I initially thought, because we
want to check the pins before we allocate memory. Otherwise we would
have a possibly large number of memory allocation and freeing cycles
until GPIO pins are finally available.
I wrote this quite some time ago already, but I do not have any system
to test it. I would appreciate if one or more users of the i2c-gpio
driver could give it a try and confirm it works as intended, or at
least doesn't introduce any regression. Thanks.
drivers/i2c/busses/i2c-gpio.c | 75 ++++++++++++++++++++++++++++--------------
1 file changed, 50 insertions(+), 25 deletions(-)
--- linux-3.8-rc2.orig/drivers/i2c/busses/i2c-gpio.c 2013-01-09 22:26:30.031060312 +0100
+++ linux-3.8-rc2/drivers/i2c/busses/i2c-gpio.c 2013-01-09 22:32:59.950308645 +0100
@@ -85,23 +85,29 @@ static int i2c_gpio_getscl(void *data)
return gpio_get_value(pdata->scl_pin);
}
-static int of_i2c_gpio_probe(struct device_node *np,
- struct i2c_gpio_platform_data *pdata)
+static int of_i2c_gpio_get_pins(struct device_node *np,
+ unsigned int *sda_pin, unsigned int *scl_pin)
{
- u32 reg;
-
if (of_gpio_count(np) < 2)
return -ENODEV;
- pdata->sda_pin = of_get_gpio(np, 0);
- pdata->scl_pin = of_get_gpio(np, 1);
+ *sda_pin = of_get_gpio(np, 0);
+ *scl_pin = of_get_gpio(np, 1);
- if (!gpio_is_valid(pdata->sda_pin) || !gpio_is_valid(pdata->scl_pin)) {
+ if (!gpio_is_valid(*sda_pin) || !gpio_is_valid(*scl_pin)) {
pr_err("%s: invalid GPIO pins, sda=%d/scl=%d\n",
- np->full_name, pdata->sda_pin, pdata->scl_pin);
+ np->full_name, *sda_pin, *scl_pin);
return -ENODEV;
}
+ return 0;
+}
+
+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", ®))
@@ -113,8 +119,6 @@ static int of_i2c_gpio_probe(struct devi
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");
-
- return 0;
}
static int i2c_gpio_probe(struct platform_device *pdev)
@@ -123,31 +127,52 @@ static int i2c_gpio_probe(struct platfor
struct i2c_gpio_platform_data *pdata;
struct i2c_algo_bit_data *bit_data;
struct i2c_adapter *adap;
+ unsigned int sda_pin, scl_pin;
int ret;
- priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
- if (!priv)
- return -ENOMEM;
- adap = &priv->adap;
- bit_data = &priv->bit_data;
- pdata = &priv->pdata;
-
+ /* First get the GPIO pins; if it fails, we'll defer the probe. */
if (pdev->dev.of_node) {
- ret = of_i2c_gpio_probe(pdev->dev.of_node, pdata);
+ ret = of_i2c_gpio_get_pins(pdev->dev.of_node,
+ &sda_pin, &scl_pin);
if (ret)
return ret;
} else {
if (!pdev->dev.platform_data)
return -ENXIO;
- memcpy(pdata, pdev->dev.platform_data, sizeof(*pdata));
+ pdata = pdev->dev.platform_data;
+ sda_pin = pdata->sda_pin;
+ scl_pin = pdata->scl_pin;
}
- ret = gpio_request(pdata->sda_pin, "sda");
- if (ret)
+ ret = gpio_request(sda_pin, "sda");
+ if (ret) {
+ if (ret == -EINVAL)
+ ret = -EPROBE_DEFER; /* Try again later */
goto err_request_sda;
- ret = gpio_request(pdata->scl_pin, "scl");
- if (ret)
+ }
+ ret = gpio_request(scl_pin, "scl");
+ if (ret) {
+ if (ret == -EINVAL)
+ ret = -EPROBE_DEFER; /* Try again later */
goto err_request_scl;
+ }
+
+ priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv) {
+ ret = -ENOMEM;
+ goto err_add_bus;
+ }
+ adap = &priv->adap;
+ bit_data = &priv->bit_data;
+ pdata = &priv->pdata;
+
+ if (pdev->dev.of_node) {
+ pdata->sda_pin = sda_pin;
+ pdata->scl_pin = scl_pin;
+ of_i2c_gpio_get_props(pdev->dev.of_node, pdata);
+ } else {
+ memcpy(pdata, pdev->dev.platform_data, sizeof(*pdata));
+ }
if (pdata->sda_is_open_drain) {
gpio_direction_output(pdata->sda_pin, 1);
@@ -211,9 +236,9 @@ static int i2c_gpio_probe(struct platfor
return 0;
err_add_bus:
- gpio_free(pdata->scl_pin);
+ gpio_free(scl_pin);
err_request_scl:
- gpio_free(pdata->sda_pin);
+ gpio_free(sda_pin);
err_request_sda:
return ret;
}
--
Jean Delvare
--
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