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.stefane...@microchip.com>
---
MAINTAINERS | 6 +
drivers/gpio/gpio-sama5d2-piobu.c | 253 ++++++++++++++++++++++++++++++++++++++
2 files changed, 259 insertions(+)
create mode 100644 drivers/gpio/gpio-sama5d2-piobu.c
diff --git a/MAINTAINERS b/MAINTAINERS
index f485597..fadc96d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9760,6 +9760,12 @@ M: Nicolas Ferre <nicolas.fe...@microchip.com>
S: Supported
F: drivers/power/reset/at91-sama5d2_shdwc.c
+MICROCHIP SAMA5D2-COMPATIBLE PIOBU GPIO
+M: Andrei Stefanescu <andrei.stefane...@microchip.com>
+L: linux-arm-ker...@lists.infradead.org (moderated for non-subscribers)
+L: linux-g...@vger.kernel.org
+F: drivers/gpio/gpio-sama5d2-piobu.c
+
MICROCHIP SPI DRIVER
M: Nicolas Ferre <nicolas.fe...@microchip.com>
S: Supported
diff --git a/drivers/gpio/gpio-sama5d2-piobu.c
b/drivers/gpio/gpio-sama5d2-piobu.c
new file mode 100644
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.stefane...@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.stefane...@microchip.com>");
--
2.7.4
