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Message-ID: <4F67A902.40409@wwwdotorg.org>
Date: Mon, 19 Mar 2012 15:45:38 -0600
From: Stephen Warren <swarren@...dotorg.org>
To: Thomas Abraham <thomas.abraham@...aro.org>
CC: linux-arm-kernel@...ts.infradead.org, kgene.kim@...sung.com,
linus.walleij@...aro.org, linux-samsung-soc@...r.kernel.org,
linux-kernel@...r.kernel.org, patches@...aro.org
Subject: Re: [PATCH 1/5] pinctrl: add samsung pinctrl and gpiolib driver
On 03/11/2012 06:46 AM, Thomas Abraham wrote:
> Add a new pinctrl and gpiolib driver for Samsung SoC's. This driver provides a
> common framework for all Samsung SoC's to interface with the pinctrl and
> gpiolib subsystems.
>
> This driver is split into two parts: the pinctrl interface and the gpiolib
> interface. The pinctrl interface registers pinctrl devices with the pinctrl
> subsystem and gpiolib interface registers gpio chips with the gpiolib
> subsystem. The information about the pins, pin groups, pin functions and
> gpio chips, which are SoC specific, are all provided to the driver using
> driver data. The driver registers all the pinctrl devices and gpio chips
> which are found in the driver data.
> diff --git a/arch/arm/plat-samsung/include/plat/pinctrl.h b/arch/arm/plat-samsung/include/plat/pinctrl.h
It'd be nice to name this samsung-pinctrl.h, or something other than
just "pinctrl.h". That way, this new header won't cause problems for a
multi-SoC kernel in the future where multiple plat-*/include/plat or
mach-*/include/mach directories are in the include path.
> diff --git a/drivers/pinctrl/pinctrl-samsung.c b/drivers/pinctrl/pinctrl-samsung.c
> +/* check if the selector is a valid pin function selector */
> +static int samsung_pinmux_list_funcs(struct pinctrl_dev *pctldev,
> + unsigned selector)
> +{
> + struct samsung_pinctrl_drv_data *drvdata;
> +
> + drvdata = pinctrl_dev_get_drvdata(pctldev);
> + if (selector >= drvdata->nr_groups)
> + return -EINVAL;
That test should be against something other than nr_groups; nr_functions
or similar, right?
> +static void samsung_pimux_setup(struct pinctrl_dev *pctldev, unsigned selector,
s/pimux/pinmux/
...
> + const unsigned int *pin;
...
> + pin = drvdata->pin_groups[group].pins;
It might be a little clearer to rename "pin" to "pins", since it's an
array...
> +
> + /*
> + * for each pin in the pin group selected, program the correspoding pin
> + * pin function number in the config register.
> + */
> + for (cnt = 0; cnt < drvdata->pin_groups[group].num_pins; cnt++, pin++) {
> + pin_to_reg_bank(drvdata->gc, *pin - drvdata->ctrl->base,
> + ®, &pin_offset, &bank);
... and say pins[cnt] instead of *pin here (and remove pin++ from the
for loop statement)
But it's just a slight suggestion; your call.
> +static int samsung_pinmux_gpio_set_direction(struct pinctrl_dev *pctldev,
> + struct pinctrl_gpio_range *range, unsigned offset, bool input)
...
> + pin_to_reg_bank(range->gc, offset, ®, &pin_offset, &bank);
> + mask = (1 << bank->func_width) - 1;
> + shift = pin_offset * bank->func_width;
It might be useful to put those 3 lines into a helper function since
they're duplicating with samsung_pimux_setup() and similar code is in
samsung_pinconf_set() too.
> +static int samsung_pinconf_group_set(struct pinctrl_dev *pctldev,
> + unsigned group, unsigned long config)
I think you can leave out group_set(), and the pinctrl core will loop
over all pins in the group for you.
> +static void samsung_gpio_set(struct gpio_chip *gc, unsigned offset, int value)
...
> + data = readl(reg + DAT_REG);
...
> + __raw_writel(data, reg + DAT_REG);
Why sometimes use the __raw variants and sometimes not?
> +static int samsung_gpio_direction_output(struct gpio_chip *gc, unsigned offset,
> + int value)
...
> + ret = pinctrl_gpio_direction_output(gc->base + offset);
> + if (!ret)
> + samsung_gpio_set(gc, offset, value);
This will set the GPIO to output direction before programming the output
value, which might cause a glitch. You may want to try and swap those
two function calls.
> +static int __devinit samsung_pinctrl_probe(struct platform_device *pdev)
...
> + res = request_mem_region(res->start, resource_size(res),
> + pdev->name);
> + if (!res) {
> + dev_err(&pdev->dev, "request for mem region failed\n");
> + return -EBUSY;
> + }
> +
> + drvdata->virt_base = ioremap(res->start, resource_size(res));
Perhaps replace those two function calls with
devm_request_and_ioremap(), and as a bonus you won't have to unmap or
release the region either.
> + if (!drvdata->virt_base) {
> + dev_err(&pdev->dev, "ioremap failed\n");
i.e. you wouldn't have to add the missing error-handling here, and below.
> + return -EINVAL;
> + }
> +/* driver data for various samsung soc's */
> +#ifdef CONFIG_CPU_EXYNOS4210
> +
> +#define EXYNOS4210_PCTRL_DRVDATA ((kernel_ulong_t)&exynos4210_pinctrl_drv_data)
> +#else
> +#define EXYNOS4210_PCTRL_DRVDATA ((kernel_ulong_t)NULL)
> +#endif /* CONFIG_CPU_EXYNOS4210 */
Doesn't that interact badly with samsung_pinctrl_get_driver_data()
above, which just blindly adds to the .driver_data field when an entry
is found in samsung_pinctrl_driver_ids[]?
> +static struct platform_device_id samsung_pinctrl_driver_ids[] = {
> + {
> + .name = "exynos4-pinctrl",
> + .driver_data = EXYNOS4210_PCTRL_DRVDATA,
> + },
> + { },
> +};
> +MODULE_DEVICE_TABLE(platform, samsung_pinctrl_driver_ids);
--
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