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: Andrei Stefanescu <andrei.stefanescu@microchip.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/MAINTAINERS b/MAINTAINERS
index 65828b7..79979ca 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -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

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 06e7f9d..f479947 100644 (file)
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -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

diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 671c447..f18d345 100644 (file)
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -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

diff --git a/drivers/gpio/gpio-sama5d2-piobu.c b/drivers/gpio/gpio-sama5d2-piobu.c
new file mode 100644 (file)
index 0000000..03a0006
--- /dev/null
+++ b/drivers/gpio/gpio-sama5d2-piobu.c
@@ -0,0 +1,253 @@
+// 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>");