gpio: sifive: add support for DM based gpio driver for FU540-SoC

This patch adds a DM based driver model for gpio controller present in
FU540-C000 SoC on HiFive Unleashed A00 board. This SoC has one GPIO
bank and 16 GPIO lines in total, out of which GPIO0 to GPIO9 and
GPIO15 are routed to the J1 header on the board.

This implementation is ported from linux based gpio driver submitted
for review by Wesley W. Terpstra <wesley@sifive.com> and/or Atish Patra
<atish.patra@wdc.com> (many thanks !!). The linux driver can be referred
here [1]

[1]: https://lkml.org/lkml/2018/10/9/1103

Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

3 files changed, 185 insertions, 0 deletions

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index f2dabb5..39f2c7e 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -285,6 +285,13 @@ config STM32_GPIO
 	  usable on many stm32 families like stm32f4/f7/h7 and stm32mp1.
 	  Tested on STM32F7.
 
+config SIFIVE_GPIO
+	bool "SiFive GPIO driver"
+	depends on DM_GPIO
+	help
+	  Device model driver for GPIO controller present in SiFive FU540 SoC. This
+	  driver enables GPIO interface on HiFive Unleashed A00 board.
+
 config MVEBU_GPIO
 	bool "Marvell MVEBU GPIO driver"
 	depends on DM_GPIO && ARCH_MVEBU
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 4a8aa0f..ccc49e2 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -61,3 +61,4 @@ obj-$(CONFIG_$(SPL_)PCF8575_GPIO)	+= pcf8575_gpio.o
 obj-$(CONFIG_PM8916_GPIO)	+= pm8916_gpio.o
 obj-$(CONFIG_MT7621_GPIO)	+= mt7621_gpio.o
 obj-$(CONFIG_MSCC_SGPIO)	+= mscc_sgpio.o
+obj-$(CONFIG_SIFIVE_GPIO)	+= sifive-gpio.o
diff --git a/drivers/gpio/sifive-gpio.c b/drivers/gpio/sifive-gpio.c
new file mode 100644
index 0000000..76d5a1d3
--- /dev/null
+++ b/drivers/gpio/sifive-gpio.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * SiFive GPIO driver
+ *
+ * Copyright (C) 2019 SiFive, Inc.
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <asm/arch/gpio.h>
+#include <asm/io.h>
+#include <errno.h>
+#include <asm/gpio.h>
+
+static int sifive_gpio_probe(struct udevice *dev)
+{
+	struct sifive_gpio_platdata *plat = dev_get_platdata(dev);
+	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+	char name[18], *str;
+
+	sprintf(name, "gpio@%4lx_", (uintptr_t)plat->base);
+	str = strdup(name);
+	if (!str)
+		return -ENOMEM;
+	uc_priv->bank_name = str;
+
+	/*
+	 * Use the gpio count mentioned in device tree,
+	 * if not specified in dt, set NR_GPIOS as default
+	 */
+	uc_priv->gpio_count = dev_read_u32_default(dev, "ngpios", NR_GPIOS);
+
+	return 0;
+}
+
+static void sifive_update_gpio_reg(void *bptr, u32 offset, bool value)
+{
+	void __iomem *ptr = (void __iomem *)bptr;
+
+	u32 bit = BIT(offset);
+	u32 old = readl(ptr);
+
+	if (value)
+		writel(old | bit, ptr);
+	else
+		writel(old & ~bit, ptr);
+}
+
+static int sifive_gpio_direction_input(struct udevice *dev, u32 offset)
+{
+	struct sifive_gpio_platdata *plat = dev_get_platdata(dev);
+	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	if (offset > uc_priv->gpio_count)
+		return -EINVAL;
+
+	/* Configure gpio direction as input */
+	sifive_update_gpio_reg(plat->base + GPIO_INPUT_EN,  offset, true);
+	sifive_update_gpio_reg(plat->base + GPIO_OUTPUT_EN, offset, false);
+
+	return 0;
+}
+
+static int sifive_gpio_direction_output(struct udevice *dev, u32 offset,
+					int value)
+{
+	struct sifive_gpio_platdata *plat = dev_get_platdata(dev);
+	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	if (offset > uc_priv->gpio_count)
+		return -EINVAL;
+
+	/* Configure gpio direction as output */
+	sifive_update_gpio_reg(plat->base + GPIO_OUTPUT_EN, offset, true);
+	sifive_update_gpio_reg(plat->base + GPIO_INPUT_EN,  offset, false);
+
+	/* Set the output state of the pin */
+	sifive_update_gpio_reg(plat->base + GPIO_OUTPUT_VAL, offset, value);
+
+	return 0;
+}
+
+static int sifive_gpio_get_value(struct udevice *dev, u32 offset)
+{
+	struct sifive_gpio_platdata *plat = dev_get_platdata(dev);
+	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+	int val;
+	int dir;
+
+	if (offset > uc_priv->gpio_count)
+		return -EINVAL;
+
+	/* Get direction of the pin */
+	dir = !(readl(plat->base + GPIO_OUTPUT_EN) & BIT(offset));
+
+	if (dir)
+		val = readl(plat->base + GPIO_INPUT_VAL) & BIT(offset);
+	else
+		val = readl(plat->base + GPIO_OUTPUT_VAL) & BIT(offset);
+
+	return val ? HIGH : LOW;
+}
+
+static int sifive_gpio_set_value(struct udevice *dev, u32 offset, int value)
+{
+	struct sifive_gpio_platdata *plat = dev_get_platdata(dev);
+	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	if (offset > uc_priv->gpio_count)
+		return -EINVAL;
+
+	sifive_update_gpio_reg(plat->base + GPIO_OUTPUT_VAL, offset, value);
+
+	return 0;
+}
+
+static int sifive_gpio_get_function(struct udevice *dev, unsigned int offset)
+{
+	struct sifive_gpio_platdata *plat = dev_get_platdata(dev);
+	u32	outdir, indir, val;
+	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	if (offset > uc_priv->gpio_count)
+		return -1;
+
+	/* Get direction of the pin */
+	outdir = readl(plat->base + GPIO_OUTPUT_EN) & BIT(offset);
+	indir  = readl(plat->base + GPIO_INPUT_EN) & BIT(offset);
+
+	if (outdir)
+		/* Pin at specified offset is configured as output */
+		val = GPIOF_OUTPUT;
+	else if (indir)
+		/* Pin at specified offset is configured as input */
+		val = GPIOF_INPUT;
+	else
+		/*The requested GPIO is not set as input or output */
+		val = GPIOF_UNUSED;
+
+	return val;
+}
+
+static const struct udevice_id sifive_gpio_match[] = {
+	{ .compatible = "sifive,gpio0" },
+	{ }
+};
+
+static const struct dm_gpio_ops sifive_gpio_ops = {
+	.direction_input        = sifive_gpio_direction_input,
+	.direction_output       = sifive_gpio_direction_output,
+	.get_value              = sifive_gpio_get_value,
+	.set_value              = sifive_gpio_set_value,
+	.get_function		= sifive_gpio_get_function,
+};
+
+static int sifive_gpio_ofdata_to_platdata(struct udevice *dev)
+{
+	struct sifive_gpio_platdata *plat = dev_get_platdata(dev);
+	fdt_addr_t addr;
+
+	addr = devfdt_get_addr(dev);
+	if (addr == FDT_ADDR_T_NONE)
+		return -EINVAL;
+
+	plat->base = (void *)addr;
+	return 0;
+}
+
+U_BOOT_DRIVER(gpio_sifive) = {
+	.name	= "gpio_sifive",
+	.id	= UCLASS_GPIO,
+	.of_match = sifive_gpio_match,
+	.ofdata_to_platdata = of_match_ptr(sifive_gpio_ofdata_to_platdata),
+	.platdata_auto_alloc_size = sizeof(struct sifive_gpio_platdata),
+	.ops	= &sifive_gpio_ops,
+	.probe	= sifive_gpio_probe,
+};