linux-kernel - Re: [PATCH 2/2] gpio: Add GPIO driver for Spreadtrum SC9860 platform

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Message-ID: <20180201121753.GB690@gmail.com>
Date:   Thu, 1 Feb 2018 13:17:53 +0100
From:   Marcus Folkesson <marcus.folkesson@...il.com>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     linus.walleij@...aro.org, robh+dt@...nel.org, mark.rutland@....com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-gpio@...r.kernel.org, broonie@...nel.org
Subject: Re: [PATCH 2/2] gpio: Add GPIO driver for Spreadtrum SC9860 platform

Hi Baolin,

On Tue, Jan 30, 2018 at 08:07:43PM +0800, Baolin Wang wrote:
> The Spreadtrum SC9860 platform GPIO controller contains 16 groups and
> each group contains 16 GPIOs. Each GPIO can set input/output and has
> the interrupt capability.
> 
> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
> ---
> diff --git a/drivers/gpio/gpio-sprd.c b/drivers/gpio/gpio-sprd.c
> new file mode 100644
> index 0000000..af59b9f
> --- /dev/null
> +++ b/drivers/gpio/gpio-sprd.c
> @@ -0,0 +1,301 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2018 Spreadtrum Communications Inc.
> + * Copyright (c) 2018 Linaro Ltd.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/spinlock.h>
> +
> +/* GPIO registers definition */
> +#define SPRD_GPIO_DATA		0x0
> +#define SPRD_GPIO_DMSK		0x4
> +#define SPRD_GPIO_DIR		0x8
> +#define SPRD_GPIO_IS		0xc
> +#define SPRD_GPIO_IBE		0x10
> +#define SPRD_GPIO_IEV		0x14
> +#define SPRD_GPIO_IE		0x18
> +#define SPRD_GPIO_RIS		0x1c
> +#define SPRD_GPIO_MIS		0x20
> +#define SPRD_GPIO_IC		0x24
> +#define SPRD_GPIO_INEN		0x28
> +
> +/* We have 16 groups GPIOs and each group contain 16 GPIOs */
> +#define SPRD_GPIO_GROUP_NR	16
> +#define SPRD_GPIO_NR		256
> +#define SPRD_GPIO_GROUP_SIZE	0x80
> +#define SPRD_GPIO_GROUP_MASK	GENMASK(15, 0)
> +#define SPRD_GPIO_BIT(x)	((x) & (SPRD_GPIO_GROUP_NR - 1))
> +
> +struct sprd_gpio {
> +	struct gpio_chip chip;
> +	void __iomem *base;
> +	spinlock_t lock;
> +	int irq;
> +};
> +
> +static inline void __iomem *sprd_gpio_group_base(struct sprd_gpio *sprd_gpio,
> +						 unsigned int group)
> +{
> +	return sprd_gpio->base + SPRD_GPIO_GROUP_SIZE * group;
> +}
> +
> +static void sprd_gpio_update(struct gpio_chip *chip, unsigned int offset,
> +			     unsigned int reg, unsigned int val)
> +{
> +	struct sprd_gpio *sprd_gpio = gpiochip_get_data(chip);
> +	void __iomem *base = sprd_gpio_group_base(sprd_gpio,
> +						  offset / SPRD_GPIO_GROUP_NR);
> +	u32 shift = SPRD_GPIO_BIT(offset);
> +	unsigned long flags;
> +	u32 orig, tmp;
> +
> +	spin_lock_irqsave(&sprd_gpio->lock, flags);
> +	orig = readl_relaxed(base + reg);
> +
> +	tmp = (orig & ~BIT(shift)) | (val << shift);
> +	writel_relaxed(tmp, base + reg);
> +	spin_unlock_irqrestore(&sprd_gpio->lock, flags);
> +}
> +
> +static int sprd_gpio_read(struct gpio_chip *chip, unsigned int offset,
> +			  unsigned int reg)
> +{
> +	struct sprd_gpio *sprd_gpio = gpiochip_get_data(chip);
> +	void __iomem *base = sprd_gpio_group_base(sprd_gpio,
> +						  offset / SPRD_GPIO_GROUP_NR);
> +	u32 value = readl_relaxed(base + reg) & SPRD_GPIO_GROUP_MASK;
> +	u32 shift = SPRD_GPIO_BIT(offset);
> +
> +	return !!(value & BIT(shift));
> +}
> +
> +static int sprd_gpio_request(struct gpio_chip *chip, unsigned int offset)
> +{
> +	sprd_gpio_update(chip, offset, SPRD_GPIO_DMSK, 1);
> +	return 0;
> +}

Better to change the function to void since the return value is not
valueable.

> +
> +static void sprd_gpio_free(struct gpio_chip *chip, unsigned int offset)
> +{
> +	sprd_gpio_update(chip, offset, SPRD_GPIO_DMSK, 0);
> +}
> +
> +static int sprd_gpio_direction_input(struct gpio_chip *chip,
> +				     unsigned int offset)
> +{
> +	sprd_gpio_update(chip, offset, SPRD_GPIO_DIR, 0);
> +	sprd_gpio_update(chip, offset, SPRD_GPIO_INEN, 1);
> +	return 0;
> +}

Same here


> +
> +static int sprd_gpio_direction_output(struct gpio_chip *chip,
> +				      unsigned int offset, int value)
> +{
> +	sprd_gpio_update(chip, offset, SPRD_GPIO_DIR, 1);
> +	sprd_gpio_update(chip, offset, SPRD_GPIO_INEN, 0);
> +	sprd_gpio_update(chip, offset, SPRD_GPIO_DATA, value);
> +	return 0;
> +}

and here.


Thanks,
Marcus Folkesson




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