Commit fb0b35d3 authored by Andrei.Stefanescu@microchip.com's avatar Andrei.Stefanescu@microchip.com Committed by Linus Walleij
Browse files

gpio: add driver for SAMA5D2 PIOBU pins 



PIOBU pins do not lose their voltage during Backup/Self-refresh.
This patch adds a simple GPIO controller for them and a
maintainer for the driver.

This driver adds support for using the pins as GPIO
offering the possibility to read/set the voltage.

Signed-off-by: default avatarAndrei Stefanescu <andrei.stefanescu@microchip.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent 6bd925a8

MAINTAINERS

+6 −0
Original line number Diff line number Diff line
@@ -9768,6 +9768,12 @@ M: Nicolas Ferre <nicolas.ferre@microchip.com> 
S:	Supported

F:	drivers/power/reset/at91-sama5d2_shdwc.c



MICROCHIP SAMA5D2-COMPATIBLE PIOBU GPIO

M:	Andrei Stefanescu <andrei.stefanescu@microchip.com>

L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)

L:	linux-gpio@vger.kernel.org

F:	drivers/gpio/gpio-sama5d2-piobu.c



MICROCHIP SPI DRIVER

M:	Nicolas Ferre <nicolas.ferre@microchip.com>

S:	Supported

drivers/gpio/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -430,6 +430,17 @@ config GPIO_REG 
	  A 32-bit single register GPIO fixed in/out implementation.  This

	  can be used to represent any register as a set of GPIO signals.



config GPIO_SAMA5D2_PIOBU

	tristate "SAMA5D2 PIOBU GPIO support"

	depends on MFD_SYSCON

	select GPIO_SYSCON

	help

	  Say yes here to use the PIOBU pins as GPIOs.



	  PIOBU pins on the SAMA5D2 can be used as GPIOs.

	  The difference from regular GPIOs is that they

	  maintain their value during backup/self-refresh.



config GPIO_SIOX

	tristate "SIOX GPIO support"

	depends on SIOX

drivers/gpio/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -108,6 +108,7 @@ obj-$(CONFIG_GPIO_RDC321X) += gpio-rdc321x.o 
obj-$(CONFIG_GPIO_RCAR)		+= gpio-rcar.o

obj-$(CONFIG_GPIO_REG)		+= gpio-reg.o

obj-$(CONFIG_ARCH_SA1100)	+= gpio-sa1100.o

obj-$(CONFIG_GPIO_SAMA5D2_PIOBU)	+= gpio-sama5d2-piobu.o

obj-$(CONFIG_GPIO_SCH)		+= gpio-sch.o

obj-$(CONFIG_GPIO_SCH311X)	+= gpio-sch311x.o

obj-$(CONFIG_GPIO_SNPS_CREG)	+= gpio-creg-snps.o

drivers/gpio/gpio-sama5d2-piobu.c

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// SPDX-License-Identifier: GPL-2.0

/*

 * SAMA5D2 PIOBU GPIO controller

 *

 * Copyright (C) 2018 Microchip Technology Inc. and its subsidiaries

 *

 * Author: Andrei Stefanescu <andrei.stefanescu@microchip.com>

 *

 */

#include <linux/bits.h>

#include <linux/gpio/driver.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/mfd/syscon.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/platform_device.h>

#include <linux/regmap.h>



#define PIOBU_NUM 8

#define PIOBU_REG_SIZE 4



/*

 * backup mode protection register for tamper detection

 * normal mode protection register for tamper detection

 * wakeup signal generation

 */

#define PIOBU_BMPR 0x7C

#define PIOBU_NMPR 0x80

#define PIOBU_WKPR 0x90



#define PIOBU_BASE 0x18 /* PIOBU offset from SECUMOD base register address. */



#define PIOBU_DET_OFFSET 16



/* In the datasheet this bit is called OUTPUT */

#define PIOBU_DIRECTION BIT(8)

#define PIOBU_OUT BIT(8)

#define PIOBU_IN 0



#define PIOBU_SOD BIT(9)

#define PIOBU_PDS BIT(10)



#define PIOBU_HIGH BIT(9)

#define PIOBU_LOW 0



struct sama5d2_piobu {

	struct gpio_chip chip;

	struct regmap *regmap;

};



/**

 * sama5d2_piobu_setup_pin() - prepares a pin for set_direction call

 *

 * Do not consider pin for tamper detection (normal and backup modes)

 * Do not consider pin as tamper wakeup interrupt source

 */

static int sama5d2_piobu_setup_pin(struct gpio_chip *chip, unsigned int pin)

{

	int ret;

	struct sama5d2_piobu *piobu = container_of(chip, struct sama5d2_piobu,

						   chip);

	unsigned int mask = BIT(PIOBU_DET_OFFSET + pin);



	ret = regmap_update_bits(piobu->regmap, PIOBU_BMPR, mask, 0);

	if (ret)

		return ret;



	ret = regmap_update_bits(piobu->regmap, PIOBU_NMPR, mask, 0);

	if (ret)

		return ret;



	return regmap_update_bits(piobu->regmap, PIOBU_WKPR, mask, 0);

}



/**

 * sama5d2_piobu_write_value() - writes value & mask at the pin's PIOBU register

 */

static int sama5d2_piobu_write_value(struct gpio_chip *chip, unsigned int pin,

				     unsigned int mask, unsigned int value)

{

	int reg;

	struct sama5d2_piobu *piobu = container_of(chip, struct sama5d2_piobu,

						   chip);



	reg = PIOBU_BASE + pin * PIOBU_REG_SIZE;



	return regmap_update_bits(piobu->regmap, reg, mask, value);

}



/**

 * sama5d2_piobu_read_value() - read the value with masking from the pin's PIOBU

 *			      register

 */

static int sama5d2_piobu_read_value(struct gpio_chip *chip, unsigned int pin,

				    unsigned int mask)

{

	struct sama5d2_piobu *piobu = container_of(chip, struct sama5d2_piobu,

						   chip);

	unsigned int val, reg;

	int ret;



	reg = PIOBU_BASE + pin * PIOBU_REG_SIZE;

	ret = regmap_read(piobu->regmap, reg, &val);

	if (ret < 0)

		return ret;



	return val & mask;

}



/**

 * sama5d2_piobu_set_direction() - mark pin as input or output

 */

static int sama5d2_piobu_set_direction(struct gpio_chip *chip,

				       unsigned int direction,

				       unsigned int pin)

{

	return sama5d2_piobu_write_value(chip, pin, PIOBU_DIRECTION, direction);

}



/**

 * sama5d2_piobu_get_direction() - gpiochip get_direction

 */

static int sama5d2_piobu_get_direction(struct gpio_chip *chip,

				       unsigned int pin)

{

	int ret = sama5d2_piobu_read_value(chip, pin, PIOBU_DIRECTION);



	if (ret < 0)

		return ret;



	return (ret == PIOBU_IN) ? 1 : 0;

}



/**

 * sama5d2_piobu_direction_input() - gpiochip direction_input

 */

static int sama5d2_piobu_direction_input(struct gpio_chip *chip,

					 unsigned int pin)

{

	return sama5d2_piobu_set_direction(chip, PIOBU_IN, pin);

}



/**

 * sama5d2_piobu_direction_output() - gpiochip direction_output

 */

static int sama5d2_piobu_direction_output(struct gpio_chip *chip,

					  unsigned int pin, int value)

{

	return sama5d2_piobu_set_direction(chip, PIOBU_OUT, pin);

}



/**

 * sama5d2_piobu_get() - gpiochip get

 */

static int sama5d2_piobu_get(struct gpio_chip *chip, unsigned int pin)

{

	/* if pin is input, read value from PDS else read from SOD */

	int ret = sama5d2_piobu_get_direction(chip, pin);



	if (ret == 1)

		ret = sama5d2_piobu_read_value(chip, pin, PIOBU_PDS);

	else if (!ret)

		ret = sama5d2_piobu_read_value(chip, pin, PIOBU_SOD);



	if (ret < 0)

		return ret;



	return !!ret;

}



/**

 * sama5d2_piobu_set() - gpiochip set

 */

static void sama5d2_piobu_set(struct gpio_chip *chip, unsigned int pin,

			      int value)

{

	if (!value)

		value = PIOBU_LOW;

	else

		value = PIOBU_HIGH;



	sama5d2_piobu_write_value(chip, pin, PIOBU_SOD, value);

}



static int sama5d2_piobu_probe(struct platform_device *pdev)

{

	struct sama5d2_piobu *piobu;

	int ret, i;



	piobu = devm_kzalloc(&pdev->dev, sizeof(*piobu), GFP_KERNEL);

	if (!piobu)

		return -ENOMEM;



	platform_set_drvdata(pdev, piobu);

	piobu->chip.label = pdev->name;

	piobu->chip.parent = &pdev->dev;

	piobu->chip.of_node = pdev->dev.of_node;

	piobu->chip.owner = THIS_MODULE,

	piobu->chip.get_direction = sama5d2_piobu_get_direction,

	piobu->chip.direction_input = sama5d2_piobu_direction_input,

	piobu->chip.direction_output = sama5d2_piobu_direction_output,

	piobu->chip.get = sama5d2_piobu_get,

	piobu->chip.set = sama5d2_piobu_set,

	piobu->chip.base = -1,

	piobu->chip.ngpio = PIOBU_NUM,

	piobu->chip.can_sleep = 0,



	piobu->regmap = syscon_node_to_regmap(pdev->dev.of_node);

	if (IS_ERR(piobu->regmap)) {

		dev_err(&pdev->dev, "Failed to get syscon regmap %ld\n",

			PTR_ERR(piobu->regmap));

		return PTR_ERR(piobu->regmap);

	}



	ret = devm_gpiochip_add_data(&pdev->dev, &piobu->chip, piobu);

	if (ret) {

		dev_err(&pdev->dev, "Failed to add gpiochip %d\n", ret);

		return ret;

	}



	for (i = 0; i < PIOBU_NUM; ++i) {

		ret = sama5d2_piobu_setup_pin(&piobu->chip, i);

		if (ret) {

			dev_err(&pdev->dev, "Failed to setup pin: %d %d\n",

				i, ret);

			return ret;

		}

	}



	return 0;

}



static const struct of_device_id sama5d2_piobu_ids[] = {

	{ .compatible = "atmel,sama5d2-secumod" },

	{},

};

MODULE_DEVICE_TABLE(of, sama5d2_piobu_ids);



static struct platform_driver sama5d2_piobu_driver = {

	.driver = {

		.name		= "sama5d2-piobu",

		.of_match_table	= of_match_ptr(sama5d2_piobu_ids)

	},

	.probe = sama5d2_piobu_probe,

};



module_platform_driver(sama5d2_piobu_driver);



MODULE_VERSION("1.0");

MODULE_LICENSE("GPL v2");

MODULE_DESCRIPTION("SAMA5D2 PIOBU controller driver");

MODULE_AUTHOR("Andrei Stefanescu <andrei.stefanescu@microchip.com>");