lib: utils/gpio: Add minimal SiFive GPIO driver

We add a minimal SiFive GPIO driver so that we can do GPIO based
system power-off and reset.

Signed-off-by: Green Wan <green.wan@sifive.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>

lib/utils/gpio/fdt_gpio.c

@@ -12,7 +12,10 @@
 #include <sbi_utils/fdt/fdt_helper.h>
 #include <sbi_utils/gpio/fdt_gpio.h>
 
+extern struct fdt_gpio fdt_gpio_sifive;
+
 static struct fdt_gpio *gpio_drivers[] = {
+	&fdt_gpio_sifive
 };
 
 static struct fdt_gpio *fdt_gpio_driver(struct gpio_chip *chip)

lib/utils/gpio/fdt_gpio_sifive.c

@@ -0,0 +1,105 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2021 SiFive
+ *
+ * Authors:
+ *   Green Wan <green.wan@sifive.com>
+ */
+
+#include <sbi/riscv_io.h>
+#include <sbi/sbi_error.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/gpio/fdt_gpio.h>
+
+#define SIFIVE_GPIO_CHIP_MAX	2
+
+#define SIFIVE_GPIO_PINS_MIN	1
+#define SIFIVE_GPIO_PINS_MAX	32
+#define SIFIVE_GPIO_PINS_DEF	16
+
+#define SIFIVE_GPIO_OUTEN	0x8
+#define SIFIVE_GPIO_OUTVAL	0xc
+#define SIFIVE_GPIO_BIT(b)	(1U << (b))
+
+struct sifive_gpio_chip {
+	unsigned long addr;
+	struct gpio_chip chip;
+};
+
+static unsigned int sifive_gpio_chip_count;
+static struct sifive_gpio_chip sifive_gpio_chip_array[SIFIVE_GPIO_CHIP_MAX];
+
+static int sifive_gpio_direction_output(struct gpio_pin *gp, int value)
+{
+	unsigned int v;
+	struct sifive_gpio_chip *chip =
+		container_of(gp->chip, struct sifive_gpio_chip, chip);
+
+	v = readl((volatile void *)(chip->addr + SIFIVE_GPIO_OUTEN));
+	v |= SIFIVE_GPIO_BIT(gp->offset);
+	writel(v, (volatile void *)(chip->addr + SIFIVE_GPIO_OUTEN));
+
+	v = readl((volatile void *)(chip->addr + SIFIVE_GPIO_OUTVAL));
+	if (!value)
+		v &= ~SIFIVE_GPIO_BIT(gp->offset);
+	else
+		v |= SIFIVE_GPIO_BIT(gp->offset);
+	writel(v, (volatile void *)(chip->addr + SIFIVE_GPIO_OUTVAL));
+
+	return 0;
+}
+
+static void sifive_gpio_set(struct gpio_pin *gp, int value)
+{
+	unsigned int v;
+	struct sifive_gpio_chip *chip =
+		container_of(gp->chip, struct sifive_gpio_chip, chip);
+
+	v = readl((volatile void *)(chip->addr + SIFIVE_GPIO_OUTVAL));
+	if (!value)
+		v &= ~SIFIVE_GPIO_BIT(gp->offset);
+	else
+		v |= SIFIVE_GPIO_BIT(gp->offset);
+	writel(v, (volatile void *)(chip->addr + SIFIVE_GPIO_OUTVAL));
+}
+
+extern struct fdt_gpio fdt_gpio_sifive;
+
+static int sifive_gpio_init(void *fdt, int nodeoff, u32 phandle,
+			    const struct fdt_match *match)
+{
+	int rc;
+	struct sifive_gpio_chip *chip;
+
+	if (SIFIVE_GPIO_CHIP_MAX <= sifive_gpio_chip_count)
+		return SBI_ENOSPC;
+	chip = &sifive_gpio_chip_array[sifive_gpio_chip_count];
+
+	rc = fdt_get_node_addr_size(fdt, nodeoff, &chip->addr, NULL);
+	if (rc)
+		return rc;
+
+	chip->chip.driver = &fdt_gpio_sifive;
+	chip->chip.id = phandle;
+	chip->chip.ngpio = SIFIVE_GPIO_PINS_DEF;
+	chip->chip.direction_output = sifive_gpio_direction_output;
+	chip->chip.set = sifive_gpio_set;
+	rc = gpio_chip_add(&chip->chip);
+	if (rc)
+		return rc;
+
+	sifive_gpio_chip_count++;
+	return 0;
+}
+
+static const struct fdt_match sifive_gpio_match[] = {
+	{ .compatible = "sifive,gpio0" },
+	{ },
+};
+
+struct fdt_gpio fdt_gpio_sifive = {
+	.match_table = sifive_gpio_match,
+	.xlate = fdt_gpio_simple_xlate,
+	.init = sifive_gpio_init,
+};

lib/utils/gpio/objects.mk

@@ -8,4 +8,5 @@
 #
 
 libsbiutils-objs-y += gpio/fdt_gpio.o
+libsbiutils-objs-y += gpio/fdt_gpio_sifive.o
 libsbiutils-objs-y += gpio/gpio.o