gpio: add Xilinx Zynq PS GPIO driver

Most of the code is taken (and adapted) from Linux kernel driver.

Just add CONFIG_ZYNQ_GPIO to you config to enable it

Signed-off-by: Andrea Scian <andrea.scian@dave.eu>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

1 files changed, 220 insertions, 0 deletions

diff --git a/drivers/gpio/zynq_gpio.c b/drivers/gpio/zynq_gpio.c
new file mode 100644
index 0000000000..83a2c465d0
--- /dev/null
+++ b/drivers/gpio/zynq_gpio.c
@@ -0,0 +1,220 @@
+/*
+ * Xilinx Zynq GPIO device driver
+ *
+ * Copyright (C) 2015 DAVE Embedded Systems <devel@dave.eu>
+ *
+ * Most of code taken from linux kernel driver (linux/drivers/gpio/gpio-zynq.c)
+ * Copyright (C) 2009 - 2014 Xilinx, Inc.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <asm/gpio.h>
+#include <asm/io.h>
+#include <asm/errno.h>
+
+/**
+ * zynq_gpio_get_bank_pin - Get the bank number and pin number within that bank
+ * for a given pin in the GPIO device
+ * @pin_num:	gpio pin number within the device
+ * @bank_num:	an output parameter used to return the bank number of the gpio
+ *		pin
+ * @bank_pin_num: an output parameter used to return pin number within a bank
+ *		  for the given gpio pin
+ *
+ * Returns the bank number and pin offset within the bank.
+ */
+static inline void zynq_gpio_get_bank_pin(unsigned int pin_num,
+					  unsigned int *bank_num,
+					  unsigned int *bank_pin_num)
+{
+	switch (pin_num) {
+	case ZYNQ_GPIO_BANK0_PIN_MIN ... ZYNQ_GPIO_BANK0_PIN_MAX:
+		*bank_num = 0;
+		*bank_pin_num = pin_num;
+		break;
+	case ZYNQ_GPIO_BANK1_PIN_MIN ... ZYNQ_GPIO_BANK1_PIN_MAX:
+		*bank_num = 1;
+		*bank_pin_num = pin_num - ZYNQ_GPIO_BANK1_PIN_MIN;
+		break;
+	case ZYNQ_GPIO_BANK2_PIN_MIN ... ZYNQ_GPIO_BANK2_PIN_MAX:
+		*bank_num = 2;
+		*bank_pin_num = pin_num - ZYNQ_GPIO_BANK2_PIN_MIN;
+		break;
+	case ZYNQ_GPIO_BANK3_PIN_MIN ... ZYNQ_GPIO_BANK3_PIN_MAX:
+		*bank_num = 3;
+		*bank_pin_num = pin_num - ZYNQ_GPIO_BANK3_PIN_MIN;
+		break;
+	default:
+		printf("invalid GPIO pin number: %u\n", pin_num);
+		*bank_num = 0;
+		*bank_pin_num = 0;
+		break;
+	}
+}
+
+int gpio_is_valid(unsigned gpio)
+{
+	return (gpio >= 0) && (gpio < ZYNQ_GPIO_NR_GPIOS);
+}
+
+static int check_gpio(unsigned gpio)
+{
+	if (!gpio_is_valid(gpio)) {
+		printf("ERROR : check_gpio: invalid GPIO %d\n", gpio);
+		return -1;
+	}
+	return 0;
+}
+
+/**
+ * gpio_get_value - Get the state of the specified pin of GPIO device
+ * @gpio:	gpio pin number within the device
+ *
+ * This function reads the state of the specified pin of the GPIO device.
+ *
+ * Return: 0 if the pin is low, 1 if pin is high.
+ */
+int gpio_get_value(unsigned gpio)
+{
+	u32 data;
+	unsigned int bank_num, bank_pin_num;
+
+	if (check_gpio(gpio) < 0)
+		return -1;
+
+	zynq_gpio_get_bank_pin(gpio, &bank_num, &bank_pin_num);
+
+	data = readl(ZYNQ_GPIO_BASE_ADDRESS +
+			     ZYNQ_GPIO_DATA_RO_OFFSET(bank_num));
+
+	return (data >> bank_pin_num) & 1;
+}
+
+/**
+ * gpio_set_value - Modify the value of the pin with specified value
+ * @gpio:	gpio pin number within the device
+ * @value:	value used to modify the value of the specified pin
+ *
+ * This function calculates the register offset (i.e to lower 16 bits or
+ * upper 16 bits) based on the given pin number and sets the value of a
+ * gpio pin to the specified value. The value is either 0 or non-zero.
+ */
+int gpio_set_value(unsigned gpio, int value)
+{
+	unsigned int reg_offset, bank_num, bank_pin_num;
+
+	if (check_gpio(gpio) < 0)
+		return -1;
+
+	zynq_gpio_get_bank_pin(gpio, &bank_num, &bank_pin_num);
+
+	if (bank_pin_num >= ZYNQ_GPIO_MID_PIN_NUM) {
+		/* only 16 data bits in bit maskable reg */
+		bank_pin_num -= ZYNQ_GPIO_MID_PIN_NUM;
+		reg_offset = ZYNQ_GPIO_DATA_MSW_OFFSET(bank_num);
+	} else {
+		reg_offset = ZYNQ_GPIO_DATA_LSW_OFFSET(bank_num);
+	}
+
+	/*
+	 * get the 32 bit value to be written to the mask/data register where
+	 * the upper 16 bits is the mask and lower 16 bits is the data
+	 */
+	value = !!value;
+	value = ~(1 << (bank_pin_num + ZYNQ_GPIO_MID_PIN_NUM)) &
+		((value << bank_pin_num) | ZYNQ_GPIO_UPPER_MASK);
+
+	writel(value, ZYNQ_GPIO_BASE_ADDRESS + reg_offset);
+
+	return 0;
+}
+
+/**
+ * gpio_direction_input - Set the direction of the specified GPIO pin as input
+ * @gpio:	gpio pin number within the device
+ *
+ * This function uses the read-modify-write sequence to set the direction of
+ * the gpio pin as input.
+ *
+ * Return: -1 if invalid gpio specified, 0 if successul
+ */
+int gpio_direction_input(unsigned gpio)
+{
+	u32 reg;
+	unsigned int bank_num, bank_pin_num;
+
+	if (check_gpio(gpio) < 0)
+		return -1;
+
+	zynq_gpio_get_bank_pin(gpio, &bank_num, &bank_pin_num);
+
+	/* bank 0 pins 7 and 8 are special and cannot be used as inputs */
+	if (bank_num == 0 && (bank_pin_num == 7 || bank_pin_num == 8))
+		return -1;
+
+	/* clear the bit in direction mode reg to set the pin as input */
+	reg = readl(ZYNQ_GPIO_BASE_ADDRESS + ZYNQ_GPIO_DIRM_OFFSET(bank_num));
+	reg &= ~BIT(bank_pin_num);
+	writel(reg, ZYNQ_GPIO_BASE_ADDRESS + ZYNQ_GPIO_DIRM_OFFSET(bank_num));
+
+	return 0;
+}
+
+/**
+ * gpio_direction_output - Set the direction of the specified GPIO pin as output
+ * @gpio:	gpio pin number within the device
+ * @value:	value to be written to specified pin
+ *
+ * This function sets the direction of specified GPIO pin as output, configures
+ * the Output Enable register for the pin and uses zynq_gpio_set to set
+ * the value of the pin to the value specified.
+ *
+ * Return: 0 always
+ */
+int gpio_direction_output(unsigned gpio, int value)
+{
+	u32 reg;
+	unsigned int bank_num, bank_pin_num;
+
+	if (check_gpio(gpio) < 0)
+		return -1;
+
+	zynq_gpio_get_bank_pin(gpio, &bank_num, &bank_pin_num);
+
+	/* set the GPIO pin as output */
+	reg = readl(ZYNQ_GPIO_BASE_ADDRESS + ZYNQ_GPIO_DIRM_OFFSET(bank_num));
+	reg |= BIT(bank_pin_num);
+	writel(reg, ZYNQ_GPIO_BASE_ADDRESS + ZYNQ_GPIO_DIRM_OFFSET(bank_num));
+
+	/* configure the output enable reg for the pin */
+	reg = readl(ZYNQ_GPIO_BASE_ADDRESS + ZYNQ_GPIO_OUTEN_OFFSET(bank_num));
+	reg |= BIT(bank_pin_num);
+	writel(reg, ZYNQ_GPIO_BASE_ADDRESS + ZYNQ_GPIO_OUTEN_OFFSET(bank_num));
+
+	/* set the state of the pin */
+	gpio_set_value(gpio, value);
+	return 0;
+}
+
+/**
+ * Request a gpio before using it.
+ *
+ * NOTE: Argument 'label' is unused.
+ */
+int gpio_request(unsigned gpio, const char *label)
+{
+	if (check_gpio(gpio) < 0)
+		return -1;
+
+	return 0;
+}
+
+/**
+ * Reset and free the gpio after using it.
+ */
+int gpio_free(unsigned gpio)
+{
+	return 0;
+}