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authorJean Delvare <khali@linux-fr.org>2013-02-28 01:01:40 +0000
committerWolfram Sang <wsa@the-dreams.de>2013-03-27 08:51:50 +0100
commit1b295c839b3931244f37cb52265017b298518f69 (patch)
treec038771c40f4cd287950983f59a41ee2923f673d /drivers/i2c/busses
parent7a6674dabfe240cc7015fc201f9662d0640e8081 (diff)
downloadvexpress-lsk-1b295c839b3931244f37cb52265017b298518f69.tar.gz
i2c: gpio: Add support for deferred probing
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@linux-fr.org> Tested-by: Bo Shen <voice.shen@atmel.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c/busses')
-rw-r--r--drivers/i2c/busses/i2c-gpio.c75
1 files changed, 50 insertions, 25 deletions
diff --git a/drivers/i2c/busses/i2c-gpio.c b/drivers/i2c/busses/i2c-gpio.c
index f3fa4332bbd..bc6e139c6e7 100644
--- a/drivers/i2c/busses/i2c-gpio.c
+++ b/drivers/i2c/busses/i2c-gpio.c
@@ -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", &reg))
@@ -113,8 +119,6 @@ static int of_i2c_gpio_probe(struct device_node *np,
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 platform_device *pdev)
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 platform_device *pdev)
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;
}