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Subject[PATCH v2 3/3] i2c-mux-gpio: Create of-based GPIOs request method
Date
Most modern platforms provide a dts with description of the devices
available in the system. It may also include i2c-gpio-mux'es.
Up until now the i2c-mux-gpio driver supported it' dts nodes, but
performed the GPIOs request by means of legacy GPIO API, which by design
and due to being legacy doesn't know anything about of/dtb/fdt/dts stuff.
It means even though the i2c-gpio-mux dts nodes are successfully mapped
to the kernel i2c-mux devices, the GPIOs used for initialization are
requested without OF_GPIO_* flags setup. It causes problems on the
platforms which fully rely on dts and reside, for instance,
i2c-gpio-muxes with active low, push-pull, open drain or open source
GPIOs connected.

It is fixed by implementing a dedicated method for full dts-based
GPIOs requests. It is mostly similar to the platform one, but
utilizes the gpiod_get_from_of_node() method to request the GPIOs.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>

---
Changelog v2
- Remove fallback pattern when selecting the dt- or plat-based GPIOs
request methods.
- Use a dedicated initial_state field in the "gpiomux" structure to
select a proper channel initially.
---
drivers/i2c/muxes/i2c-mux-gpio.c | 68 ++++++++++++++++++++++++--------
1 file changed, 52 insertions(+), 16 deletions(-)

diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
index e10f72706b99..d1a9c56fa1ec 100644
--- a/drivers/i2c/muxes/i2c-mux-gpio.c
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -66,8 +66,8 @@ static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
struct device_node *np = pdev->dev.of_node;
struct device_node *adapter_np, *child;
struct i2c_adapter *adapter;
- unsigned *values, *gpios;
- int i = 0, ret;
+ unsigned int *values;
+ int i = 0;

if (!np)
return -ENODEV;
@@ -110,24 +110,48 @@ static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
return -EINVAL;
}

- gpios = devm_kcalloc(&pdev->dev,
- mux->data.n_gpios, sizeof(*mux->data.gpios),
- GFP_KERNEL);
- if (!gpios) {
- dev_err(&pdev->dev, "Cannot allocate gpios array");
- return -ENOMEM;
- }
+ return 0;
+}
+
+static int i2c_mux_gpio_request_dt(struct gpiomux *mux,
+ struct platform_device *pdev)
+{
+ struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
+ struct device_node *np = pdev->dev.of_node;
+ struct i2c_adapter *root;
+ struct device *gpio_dev;
+ enum gpiod_flags dflags;
+ int i, ret;
+
+ root = i2c_root_adapter(&muxc->parent->dev);

for (i = 0; i < mux->data.n_gpios; i++) {
- ret = of_get_named_gpio(np, "mux-gpios", i);
- if (ret < 0)
- return ret;
- gpios[i] = ret;
- }
+ if (mux->initial_state & (1 << i))
+ dflags = GPIOD_OUT_HIGH;
+ else
+ dflags = GPIOD_OUT_LOW;
+
+ mux->gpios[i] = gpiod_get_from_of_node(np, "mux-gpios", i,
+ dflags, "i2c-mux-gpio");
+ if (IS_ERR(mux->gpios[i])) {
+ ret = PTR_ERR(mux->gpios[i]);
+ goto err_request_gpio;
+ }
+
+ if (!muxc->mux_locked)
+ continue;

- mux->data.gpios = gpios;
+ gpio_dev = &mux->gpios[i]->gdev->dev;
+ muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
+ }

return 0;
+
+err_request_gpio:
+ for (i--; i >= 0; i--)
+ gpiod_free(mux->gpios[i]);
+
+ return ret;
}
#else
static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
@@ -135,6 +159,12 @@ static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
{
return -EINVAL;
}
+
+static int i2c_mux_gpio_request_dt(struct gpiomux *mux,
+ struct platform_device *pdev)
+{
+ return -EINVAL;
+}
#endif

static int i2c_mux_gpio_probe_plat(struct gpiomux *mux,
@@ -172,6 +202,9 @@ static int i2c_mux_gpio_request_plat(struct gpiomux *mux,
struct device *gpio_dev;
int i, ret;

+ if (!mux->data.gpios)
+ return -EINVAL;
+
root = i2c_root_adapter(&muxc->parent->dev);

for (i = 0; i < mux->data.n_gpios; i++) {
@@ -263,7 +296,10 @@ static int i2c_mux_gpio_probe(struct platform_device *pdev)
mux->initial_state = mux->data.values[0];
}

- ret = i2c_mux_gpio_request_plat(mux, pdev);
+ if (!dev_get_platdata(&pdev->dev))
+ ret = i2c_mux_gpio_request_dt(mux, pdev);
+ else
+ ret = i2c_mux_gpio_request_plat(mux, pdev);
if (ret)
goto alloc_failed;

--
2.21.0
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