gpio: add driver for Mellanox BlueField 2 GPIO controller

This patch adds support for the GPIO controller used by
Mellanox BlueField 2 SOCs.

Signed-off-by: Asmaa Mnebhi <Asmaa@mellanox.com>
Link: https://lore.kernel.org/r/1680de9eb6d2b8855228dde9a2dd065f0dcbe1fb.1583182325.git.Asmaa@mellanox.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 335 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-mlxbf2.c b/drivers/gpio/gpio-mlxbf2.c
new file mode 100644
index 000000000000..7b7085050219
--- /dev/null
+++ b/drivers/gpio/gpio-mlxbf2.c
@@ -0,0 +1,335 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/acpi.h>
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/gpio/driver.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/resource.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/version.h>
+
+/*
+ * There are 3 YU GPIO blocks:
+ * gpio[0]: HOST_GPIO0->HOST_GPIO31
+ * gpio[1]: HOST_GPIO32->HOST_GPIO63
+ * gpio[2]: HOST_GPIO64->HOST_GPIO69
+ */
+#define MLXBF2_GPIO_MAX_PINS_PER_BLOCK 32
+
+/*
+ * arm_gpio_lock register:
+ * bit[31]	lock status: active if set
+ * bit[15:0]	set lock
+ * The lock is enabled only if 0xd42f is written to this field
+ */
+#define YU_ARM_GPIO_LOCK_ADDR		0x2801088
+#define YU_ARM_GPIO_LOCK_SIZE		0x8
+#define YU_LOCK_ACTIVE_BIT(val)		(val >> 31)
+#define YU_ARM_GPIO_LOCK_ACQUIRE	0xd42f
+#define YU_ARM_GPIO_LOCK_RELEASE	0x0
+
+/*
+ * gpio[x] block registers and their offset
+ */
+#define YU_GPIO_DATAIN			0x04
+#define YU_GPIO_MODE1			0x08
+#define YU_GPIO_MODE0			0x0c
+#define YU_GPIO_DATASET			0x14
+#define YU_GPIO_DATACLEAR		0x18
+#define YU_GPIO_MODE1_CLEAR		0x50
+#define YU_GPIO_MODE0_SET		0x54
+#define YU_GPIO_MODE0_CLEAR		0x58
+
+#ifdef CONFIG_PM
+struct mlxbf2_gpio_context_save_regs {
+	u32 gpio_mode0;
+	u32 gpio_mode1;
+};
+#endif
+
+/* BlueField-2 gpio block context structure. */
+struct mlxbf2_gpio_context {
+	struct gpio_chip gc;
+
+	/* YU GPIO blocks address */
+	void __iomem *gpio_io;
+
+#ifdef CONFIG_PM
+	struct mlxbf2_gpio_context_save_regs *csave_regs;
+#endif
+};
+
+/* BlueField-2 gpio shared structure. */
+struct mlxbf2_gpio_param {
+	void __iomem *io;
+	struct resource *res;
+	struct mutex *lock;
+};
+
+static struct resource yu_arm_gpio_lock_res = {
+	.start = YU_ARM_GPIO_LOCK_ADDR,
+	.end   = YU_ARM_GPIO_LOCK_ADDR + YU_ARM_GPIO_LOCK_SIZE - 1,
+	.name  = "YU_ARM_GPIO_LOCK",
+};
+
+static DEFINE_MUTEX(yu_arm_gpio_lock_mutex);
+
+static struct mlxbf2_gpio_param yu_arm_gpio_lock_param = {
+	.res = &yu_arm_gpio_lock_res,
+	.lock = &yu_arm_gpio_lock_mutex,
+};
+
+/* Request memory region and map yu_arm_gpio_lock resource */
+static int mlxbf2_gpio_get_lock_res(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	resource_size_t size;
+	int ret = 0;
+
+	mutex_lock(yu_arm_gpio_lock_param.lock);
+
+	/* Check if the memory map already exists */
+	if (yu_arm_gpio_lock_param.io)
+		goto exit;
+
+	res = yu_arm_gpio_lock_param.res;
+	size = resource_size(res);
+
+	if (!devm_request_mem_region(dev, res->start, size, res->name)) {
+		ret = -EFAULT;
+		goto exit;
+	}
+
+	yu_arm_gpio_lock_param.io = devm_ioremap(dev, res->start, size);
+	if (IS_ERR(yu_arm_gpio_lock_param.io))
+		ret = PTR_ERR(yu_arm_gpio_lock_param.io);
+
+exit:
+	mutex_unlock(yu_arm_gpio_lock_param.lock);
+
+	return ret;
+}
+
+/*
+ * Acquire the YU arm_gpio_lock to be able to change the direction
+ * mode. If the lock_active bit is already set, return an error.
+ */
+static int mlxbf2_gpio_lock_acquire(struct mlxbf2_gpio_context *gs)
+{
+	u32 arm_gpio_lock_val;
+
+	spin_lock(&gs->gc.bgpio_lock);
+	mutex_lock(yu_arm_gpio_lock_param.lock);
+
+	arm_gpio_lock_val = readl(yu_arm_gpio_lock_param.io);
+
+	/*
+	 * When lock active bit[31] is set, ModeX is write enabled
+	 */
+	if (YU_LOCK_ACTIVE_BIT(arm_gpio_lock_val)) {
+		mutex_unlock(yu_arm_gpio_lock_param.lock);
+		spin_unlock(&gs->gc.bgpio_lock);
+		return -EINVAL;
+	}
+
+	writel(YU_ARM_GPIO_LOCK_ACQUIRE, yu_arm_gpio_lock_param.io);
+
+	return 0;
+}
+
+/*
+ * Release the YU arm_gpio_lock after changing the direction mode.
+ */
+static void mlxbf2_gpio_lock_release(struct mlxbf2_gpio_context *gs)
+{
+	writel(YU_ARM_GPIO_LOCK_RELEASE, yu_arm_gpio_lock_param.io);
+	mutex_unlock(yu_arm_gpio_lock_param.lock);
+	spin_unlock(&gs->gc.bgpio_lock);
+}
+
+/*
+ * mode0 and mode1 are both locked by the gpio_lock field.
+ *
+ * Together, mode0 and mode1 define the gpio Mode dependeing also
+ * on Reg_DataOut.
+ *
+ * {mode1,mode0}:{Reg_DataOut=0,Reg_DataOut=1}->{DataOut=0,DataOut=1}
+ *
+ * {0,0}:Reg_DataOut{0,1}->{Z,Z} Input PAD
+ * {0,1}:Reg_DataOut{0,1}->{0,1} Full drive Output PAD
+ * {1,0}:Reg_DataOut{0,1}->{0,Z} 0-set PAD to low, 1-float
+ * {1,1}:Reg_DataOut{0,1}->{Z,1} 0-float, 1-set PAD to high
+ */
+
+/*
+ * Set input direction:
+ * {mode1,mode0} = {0,0}
+ */
+static int mlxbf2_gpio_direction_input(struct gpio_chip *chip,
+				       unsigned int offset)
+{
+	struct mlxbf2_gpio_context *gs = gpiochip_get_data(chip);
+	int ret;
+
+	/*
+	 * Although the arm_gpio_lock was set in the probe function, check again
+	 * if it is still enabled to be able to write to the ModeX registers.
+	 */
+	ret = mlxbf2_gpio_lock_acquire(gs);
+	if (ret < 0)
+		return ret;
+
+	writel(BIT(offset), gs->gpio_io + YU_GPIO_MODE0_CLEAR);
+	writel(BIT(offset), gs->gpio_io + YU_GPIO_MODE1_CLEAR);
+
+	mlxbf2_gpio_lock_release(gs);
+
+	return ret;
+}
+
+/*
+ * Set output direction:
+ * {mode1,mode0} = {0,1}
+ */
+static int mlxbf2_gpio_direction_output(struct gpio_chip *chip,
+					unsigned int offset,
+					int value)
+{
+	struct mlxbf2_gpio_context *gs = gpiochip_get_data(chip);
+	int ret = 0;
+
+	/*
+	 * Although the arm_gpio_lock was set in the probe function,
+	 * check again it is still enabled to be able to write to the
+	 * ModeX registers.
+	 */
+	ret = mlxbf2_gpio_lock_acquire(gs);
+	if (ret < 0)
+		return ret;
+
+	writel(BIT(offset), gs->gpio_io + YU_GPIO_MODE1_CLEAR);
+	writel(BIT(offset), gs->gpio_io + YU_GPIO_MODE0_SET);
+
+	mlxbf2_gpio_lock_release(gs);
+
+	return ret;
+}
+
+/* BlueField-2 GPIO driver initialization routine. */
+static int
+mlxbf2_gpio_probe(struct platform_device *pdev)
+{
+	struct mlxbf2_gpio_context *gs;
+	struct device *dev = &pdev->dev;
+	struct gpio_chip *gc;
+	struct resource *res;
+	unsigned int npins;
+	int ret;
+
+	gs = devm_kzalloc(dev, sizeof(*gs), GFP_KERNEL);
+	if (!gs)
+		return -ENOMEM;
+
+	/* YU GPIO block address */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	gs->gpio_io = devm_ioremap(dev, res->start, resource_size(res));
+	if (!gs->gpio_io)
+		return -ENOMEM;
+
+	ret = mlxbf2_gpio_get_lock_res(pdev);
+	if (ret) {
+		dev_err(dev, "Failed to get yu_arm_gpio_lock resource\n");
+		return ret;
+	}
+
+	if (device_property_read_u32(dev, "npins", &npins))
+		npins = MLXBF2_GPIO_MAX_PINS_PER_BLOCK;
+
+	gc = &gs->gc;
+
+	ret = bgpio_init(gc, dev, 4,
+			gs->gpio_io + YU_GPIO_DATAIN,
+			gs->gpio_io + YU_GPIO_DATASET,
+			gs->gpio_io + YU_GPIO_DATACLEAR,
+			NULL,
+			NULL,
+			0);
+
+	gc->direction_input = mlxbf2_gpio_direction_input;
+	gc->direction_output = mlxbf2_gpio_direction_output;
+	gc->ngpio = npins;
+	gc->owner = THIS_MODULE;
+
+	platform_set_drvdata(pdev, gs);
+
+	ret = devm_gpiochip_add_data(dev, &gs->gc, gs);
+	if (ret) {
+		dev_err(dev, "Failed adding memory mapped gpiochip\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int mlxbf2_gpio_suspend(struct platform_device *pdev,
+				pm_message_t state)
+{
+	struct mlxbf2_gpio_context *gs = platform_get_drvdata(pdev);
+
+	gs->csave_regs->gpio_mode0 = readl(gs->gpio_io +
+		YU_GPIO_MODE0);
+	gs->csave_regs->gpio_mode1 = readl(gs->gpio_io +
+		YU_GPIO_MODE1);
+
+	return 0;
+}
+
+static int mlxbf2_gpio_resume(struct platform_device *pdev)
+{
+	struct mlxbf2_gpio_context *gs = platform_get_drvdata(pdev);
+
+	writel(gs->csave_regs->gpio_mode0, gs->gpio_io +
+		YU_GPIO_MODE0);
+	writel(gs->csave_regs->gpio_mode1, gs->gpio_io +
+		YU_GPIO_MODE1);
+
+	return 0;
+}
+#endif
+
+static const struct acpi_device_id mlxbf2_gpio_acpi_match[] = {
+	{ "MLNXBF22", 0 },
+	{},
+};
+MODULE_DEVICE_TABLE(acpi, mlxbf2_gpio_acpi_match);
+
+static struct platform_driver mlxbf2_gpio_driver = {
+	.driver = {
+		.name = "mlxbf2_gpio",
+		.acpi_match_table = ACPI_PTR(mlxbf2_gpio_acpi_match),
+	},
+	.probe    = mlxbf2_gpio_probe,
+#ifdef CONFIG_PM
+	.suspend  = mlxbf2_gpio_suspend,
+	.resume   = mlxbf2_gpio_resume,
+#endif
+};
+
+module_platform_driver(mlxbf2_gpio_driver);
+
+MODULE_DESCRIPTION("Mellanox BlueField-2 GPIO Driver");
+MODULE_AUTHOR("Mellanox Technologies");
+MODULE_LICENSE("GPL v2");