[PATCH 1/4] i2c/gpio-i2c add: add DT support
Karol Lewandowski
k.lewandowsk at samsung.com
Mon Feb 6 13:38:29 EST 2012
On 05.02.2012 11:38, Jean-Christophe PLAGNIOL-VILLARD wrote:
Hi!
> +Device-Tree bindings for i2c gpio driver
> +
> +Required properties:
> + - compatible = "gpio-i2c";
Driver name is "i2c-gpio" in file i2c-gpio.c. Previous version of patch
adding DT-support (prepared by Thomas Chou[1]) used i2c-gpio - could we
stick to that name?
[1] https://lkml.org/lkml/2011/2/23/584
> + - gpios: sda and scl gpio
> +
> +
> +Optional properties:
> + - gpio-i2c,sda_is_open_drain: sda as open drain
> + - gpio-i2c,scl_is_open_drain: scl as open drain
> + - gpio-i2c,scl_is_output_only: scl as output only
Most of DT-properties I've seen used hyphen, not underscore. Could we
stick to that convention?
(Nitpick: I think that "is" in property names is redundant too.)
> + - udelay: half clock cycle time in us (may depend on each platform)
Could we use "clock-frequency" as Grant have suggested during review of
previous patch to i2c-gpio?
https://lkml.org/lkml/2011/2/24/220
> + - timeout: timeout to get data
> +
> +
> +Example nodes:
> +
> +i2c-gpio at 0 {
> + compatible = "gpio-i2c";
> + gpios =<&pioA 23 0 /* sda */
> + &pioA 24 0 /* scl */
> + >;
> + gpio-i2c,sda_is_open_drain;
> + gpio-i2c,scl_is_open_drain;
> + udelay =<2>; /* ~100 kHz */
> + #address-cells =<1>;
> + #size-cells =<0>;
> +
> + rv3029c2 at 56 {
> + compatible = "rv3029c2";
> + reg =<0x56>;
> + };
> +};
> diff --git a/drivers/i2c/busses/i2c-gpio.c b/drivers/i2c/busses/i2c-gpio.c
> index a651779..6b5d794 100644
> --- a/drivers/i2c/busses/i2c-gpio.c
> +++ b/drivers/i2c/busses/i2c-gpio.c
> @@ -14,6 +14,8 @@
> #include<linux/module.h>
> #include<linux/slab.h>
> #include<linux/platform_device.h>
> +#include<linux/of_gpio.h>
> +#include<linux/of_i2c.h>
>
> #include<asm/gpio.h>
>
> @@ -78,16 +80,51 @@ 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)
> +{
> + u32 reg;
> +
if (of_gpio_count(np) < 2)
return -EINVAL;
> + pdata->sda_pin = of_get_gpio(np, 0);
> + pdata->scl_pin = of_get_gpio(np, 1);
if (pdata->sda_pin < 0 || pdata->scl_pin < 0)
return -EINVAL;
> +
> + if (of_property_read_u32(np, "udelay",®))
> + pdata->udelay = reg;
> +
> + if (of_property_read_u32(np, "timeout",®))
> + pdata->timeout = reg;
> +
> + pdata->sda_is_open_drain =
> + !!of_get_property(np, "gpio-i2c,sda_is_open_drain", NULL);
> + pdata->scl_is_open_drain =
> + !!of_get_property(np, "gpio-i2c,scl_is_open_drain", NULL);
> + pdata->scl_is_output_only =
> + !!of_get_property(np, "gpio-i2c,scl_is_output_only", NULL);
> +
> + return 0;
> +}
> +
> static int __devinit i2c_gpio_probe(struct platform_device *pdev)
> {
> struct i2c_gpio_platform_data *pdata;
> struct i2c_algo_bit_data *bit_data;
> struct i2c_adapter *adap;
> int ret;
> + int len = sizeof(struct i2c_gpio_platform_data);
>
> - pdata = pdev->dev.platform_data;
> + pdata = kzalloc(len, GFP_KERNEL);
Could you also take into account Grant's comment about private/platform
data?
https://lkml.org/lkml/2011/2/3/221
> if (!pdata)
> - return -ENXIO;
> + return -ENOMEM;
> +
> + if (pdev->dev.of_node) {
> + of_i2c_gpio_probe(pdev->dev.of_node, pdata);
Above might fail if configuration is corrupted.
> + } else {
> + if (!pdev->dev.platform_data) {
> + ret = -ENXIO;
> + goto err_alloc_adap;
> + }
> + memcpy(pdata, pdev->dev.platform_data, len);
> + }
>
> ret = -ENOMEM;
> adap = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
> @@ -143,6 +180,7 @@ static int __devinit i2c_gpio_probe(struct platform_device *pdev)
> adap->algo_data = bit_data;
> adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
> adap->dev.parent =&pdev->dev;
> + adap->dev.of_node = pdev->dev.of_node;
>
> /*
> * If "dev->id" is negative we consider it as zero.
> @@ -154,6 +192,8 @@ static int __devinit i2c_gpio_probe(struct platform_device *pdev)
> if (ret)
> goto err_add_bus;
>
> + of_i2c_register_devices(adap);
> +
> platform_set_drvdata(pdev, adap);
>
> dev_info(&pdev->dev, "using pins %u (SDA) and %u (SCL%s)\n",
> @@ -172,6 +212,7 @@ err_request_sda:
> err_alloc_bit_data:
> kfree(adap);
> err_alloc_adap:
> + kfree(pdata);
> return ret;
> }
>
> @@ -192,10 +233,20 @@ static int __devexit i2c_gpio_remove(struct platform_device *pdev)
> return 0;
> }
>
> +#if defined(CONFIG_OF)
> +static const struct of_device_id gpio_i2c_dt_ids[] = {
> + { .compatible = "gpio-i2c", },
There seem to be no good reason to make DT-compatible string different
from driver's name that's already in use:
> static struct platform_driver i2c_gpio_driver = {
> .driver = {
> .name = "i2c-gpio",
Regards,
--
Karol Lewandowski | Samsung Poland R&D Center | Linux/Platform
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