[v6 2/2] gpio: aspeed: Add SGPIO driver

[v6 2/2] gpio: aspeed: Add SGPIO driver

[Hongwei Zhang]

Add SGPIO driver support for Aspeed AST2500 SoC.

Signed-off-by: Hongwei Zhang <hongweiz@ami.com>
---
 drivers/gpio/sgpio-aspeed.c | 521 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 521 insertions(+)
 create mode 100644 drivers/gpio/sgpio-aspeed.c

diff --git a/drivers/gpio/sgpio-aspeed.c b/drivers/gpio/sgpio-aspeed.c
new file mode 100644
index 0000000..9a17b1a
--- /dev/null
+++ b/drivers/gpio/sgpio-aspeed.c
@@ -0,0 +1,521 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2019 American Megatrends International LLC.
+ *
+ * Author: Karthikeyan Mani <karthikeyanm@amiindia.co.in>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/gpio/driver.h>
+#include <linux/hashtable.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+
+#define MAX_NR_SGPIO			80
+
+#define ASPEED_SGPIO_CTRL		0x54
+
+#define ASPEED_SGPIO_PINS_MASK		GENMASK(9, 6)
+#define ASPEED_SGPIO_CLK_DIV_MASK	GENMASK(31, 16)
+#define ASPEED_SGPIO_ENABLE		BIT(0)
+
+struct aspeed_sgpio {
+	struct gpio_chip chip;
+	struct clk *pclk;
+	spinlock_t lock;
+	void __iomem *base;
+	uint32_t dir_in[3];
+	int irq;
+};
+
+struct aspeed_sgpio_bank {
+	uint16_t    val_regs;
+	uint16_t    rdata_reg;
+	uint16_t    irq_regs;
+	const char  names[4][3];
+};
+
+/*
+ * Note: The "value" register returns the input value when the GPIO is
+ *	 configured as an input.
+ *
+ *	 The "rdata" register returns the output value when the GPIO is
+ *	 configured as an output.
+ */
+static const struct aspeed_sgpio_bank aspeed_sgpio_banks[] = {
+	{
+		.val_regs = 0x0000,
+		.rdata_reg = 0x0070,
+		.irq_regs = 0x0004,
+		.names = { "A", "B", "C", "D" },
+	},
+	{
+		.val_regs = 0x001C,
+		.rdata_reg = 0x0074,
+		.irq_regs = 0x0020,
+		.names = { "E", "F", "G", "H" },
+	},
+	{
+		.val_regs = 0x0038,
+		.rdata_reg = 0x0078,
+		.irq_regs = 0x003C,
+		.names = { "I", "J" },
+	},
+};
+
+enum aspeed_sgpio_reg {
+	reg_val,
+	reg_rdata,
+	reg_irq_enable,
+	reg_irq_type0,
+	reg_irq_type1,
+	reg_irq_type2,
+	reg_irq_status,
+};
+
+#define GPIO_VAL_VALUE      0x00
+#define GPIO_IRQ_ENABLE     0x00
+#define GPIO_IRQ_TYPE0      0x04
+#define GPIO_IRQ_TYPE1      0x08
+#define GPIO_IRQ_TYPE2      0x0C
+#define GPIO_IRQ_STATUS     0x10
+
+static void __iomem *bank_reg(struct aspeed_sgpio *gpio,
+				     const struct aspeed_sgpio_bank *bank,
+				     const enum aspeed_sgpio_reg reg)
+{
+	switch (reg) {
+	case reg_val:
+		return gpio->base + bank->val_regs + GPIO_VAL_VALUE;
+	case reg_rdata:
+		return gpio->base + bank->rdata_reg;
+	case reg_irq_enable:
+		return gpio->base + bank->irq_regs + GPIO_IRQ_ENABLE;
+	case reg_irq_type0:
+		return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE0;
+	case reg_irq_type1:
+		return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE1;
+	case reg_irq_type2:
+		return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE2;
+	case reg_irq_status:
+		return gpio->base + bank->irq_regs + GPIO_IRQ_STATUS;
+	default:
+		/* acturally if code runs to here, it's an error case */
+		BUG_ON(1);
+	}
+}
+
+#define GPIO_BANK(x)    ((x) >> 5)
+#define GPIO_OFFSET(x)  ((x) & 0x1f)
+#define GPIO_BIT(x)     BIT(GPIO_OFFSET(x))
+
+static const struct aspeed_sgpio_bank *to_bank(unsigned int offset)
+{
+	unsigned int bank = GPIO_BANK(offset);
+
+	WARN_ON(bank >= ARRAY_SIZE(aspeed_sgpio_banks));
+	return &aspeed_sgpio_banks[bank];
+}
+
+static int aspeed_sgpio_get(struct gpio_chip *gc, unsigned int offset)
+{
+	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
+	const struct aspeed_sgpio_bank *bank = to_bank(offset);
+	unsigned long flags;
+	enum aspeed_sgpio_reg reg;
+	bool is_input;
+	int rc = 0;
+
+	spin_lock_irqsave(&gpio->lock, flags);
+
+	is_input = gpio->dir_in[GPIO_BANK(offset)] & GPIO_BIT(offset);
+	reg = is_input ? reg_val : reg_rdata;
+	rc = !!(ioread32(bank_reg(gpio, bank, reg)) & GPIO_BIT(offset));
+
+	spin_unlock_irqrestore(&gpio->lock, flags);
+
+	return rc;
+}
+
+static void aspeed_sgpio_set(struct gpio_chip *gc, unsigned int offset, int val)
+{
+	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
+	const struct aspeed_sgpio_bank *bank = to_bank(offset);
+	unsigned long flags;
+	void __iomem *addr;
+	u32 reg = 0;
+
+	spin_lock_irqsave(&gpio->lock, flags);
+
+	addr = bank_reg(gpio, bank, reg_val);
+
+	if (val)
+		reg |= GPIO_BIT(offset);
+	else
+		reg &= ~GPIO_BIT(offset);
+
+	iowrite32(reg, addr);
+
+	spin_unlock_irqrestore(&gpio->lock, flags);
+}
+
+static int aspeed_sgpio_dir_in(struct gpio_chip *gc, unsigned int offset)
+{
+	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&gpio->lock, flags);
+	gpio->dir_in[GPIO_BANK(offset)] |= GPIO_BIT(offset);
+	spin_unlock_irqrestore(&gpio->lock, flags);
+
+	return 0;
+}
+
+static int aspeed_sgpio_dir_out(struct gpio_chip *gc, unsigned int offset, int val)
+{
+	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&gpio->lock, flags);
+	gpio->dir_in[GPIO_BANK(offset)] &= ~GPIO_BIT(offset);
+	spin_unlock_irqrestore(&gpio->lock, flags);
+
+	aspeed_sgpio_set(gc, offset, val);
+
+	return 0;
+}
+
+static int aspeed_sgpio_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+	int dir_status;
+	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&gpio->lock, flags);
+	dir_status = gpio->dir_in[GPIO_BANK(offset)] & GPIO_BIT(offset);
+	spin_unlock_irqrestore(&gpio->lock, flags);
+
+	return dir_status;
+
+}
+
+static void irqd_to_aspeed_sgpio_data(struct irq_data *d,
+					     struct aspeed_sgpio **gpio,
+					     const struct aspeed_sgpio_bank **bank,
+					     u32 *bit, int *offset)
+{
+	struct aspeed_sgpio *internal;
+
+	*offset = irqd_to_hwirq(d);
+	internal = irq_data_get_irq_chip_data(d);
+	WARN_ON(!internal);
+
+	*gpio = internal;
+	*bank = to_bank(*offset);
+	*bit = GPIO_BIT(*offset);
+}
+
+static void aspeed_sgpio_irq_ack(struct irq_data *d)
+{
+	const struct aspeed_sgpio_bank *bank;
+	struct aspeed_sgpio *gpio;
+	unsigned long flags;
+	void __iomem *status_addr;
+	int offset;
+	u32 bit;
+
+	irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
+
+	status_addr = bank_reg(gpio, bank, reg_irq_status);
+
+	spin_lock_irqsave(&gpio->lock, flags);
+
+	iowrite32(bit, status_addr);
+
+	spin_unlock_irqrestore(&gpio->lock, flags);
+}
+
+static void aspeed_sgpio_irq_set_mask(struct irq_data *d, bool set)
+{
+	const struct aspeed_sgpio_bank *bank;
+	struct aspeed_sgpio *gpio;
+	unsigned long flags;
+	u32 reg, bit;
+	void __iomem *addr;
+	int offset;
+
+	irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
+	addr = bank_reg(gpio, bank, reg_irq_enable);
+
+	spin_lock_irqsave(&gpio->lock, flags);
+
+	reg = ioread32(addr);
+	if (set)
+		reg |= bit;
+	else
+		reg &= ~bit;
+
+	iowrite32(reg, addr);
+
+	spin_unlock_irqrestore(&gpio->lock, flags);
+}
+
+static void aspeed_sgpio_irq_mask(struct irq_data *d)
+{
+	aspeed_sgpio_irq_set_mask(d, false);
+}
+
+static void aspeed_sgpio_irq_unmask(struct irq_data *d)
+{
+	aspeed_sgpio_irq_set_mask(d, true);
+}
+
+static int aspeed_sgpio_set_type(struct irq_data *d, unsigned int type)
+{
+	u32 type0 = 0;
+	u32 type1 = 0;
+	u32 type2 = 0;
+	u32 bit, reg;
+	const struct aspeed_sgpio_bank *bank;
+	irq_flow_handler_t handler;
+	struct aspeed_sgpio *gpio;
+	unsigned long flags;
+	void __iomem *addr;
+	int offset;
+
+	irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
+
+	switch (type & IRQ_TYPE_SENSE_MASK) {
+	case IRQ_TYPE_EDGE_BOTH:
+		type2 |= bit;
+		/* fall through */
+	case IRQ_TYPE_EDGE_RISING:
+		type0 |= bit;
+		/* fall through */
+	case IRQ_TYPE_EDGE_FALLING:
+		handler = handle_edge_irq;
+		break;
+	case IRQ_TYPE_LEVEL_HIGH:
+		type0 |= bit;
+		/* fall through */
+	case IRQ_TYPE_LEVEL_LOW:
+		type1 |= bit;
+		handler = handle_level_irq;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&gpio->lock, flags);
+
+	addr = bank_reg(gpio, bank, reg_irq_type0);
+	reg = ioread32(addr);
+	reg = (reg & ~bit) | type0;
+	iowrite32(reg, addr);
+
+	addr = bank_reg(gpio, bank, reg_irq_type1);
+	reg = ioread32(addr);
+	reg = (reg & ~bit) | type1;
+	iowrite32(reg, addr);
+
+	addr = bank_reg(gpio, bank, reg_irq_type2);
+	reg = ioread32(addr);
+	reg = (reg & ~bit) | type2;
+	iowrite32(reg, addr);
+
+	spin_unlock_irqrestore(&gpio->lock, flags);
+
+	irq_set_handler_locked(d, handler);
+
+	return 0;
+}
+
+static void aspeed_sgpio_irq_handler(struct irq_desc *desc)
+{
+	struct gpio_chip *gc = irq_desc_get_handler_data(desc);
+	struct irq_chip *ic = irq_desc_get_chip(desc);
+	struct aspeed_sgpio *data = gpiochip_get_data(gc);
+	unsigned int i, p, girq;
+	unsigned long reg;
+
+	chained_irq_enter(ic, desc);
+
+	for (i = 0; i < ARRAY_SIZE(aspeed_sgpio_banks); i++) {
+		const struct aspeed_sgpio_bank *bank = &aspeed_sgpio_banks[i];
+
+		reg = ioread32(bank_reg(data, bank, reg_irq_status));
+
+		for_each_set_bit(p, &reg, 32) {
+			girq = irq_find_mapping(gc->irq.domain, i * 32 + p);
+			generic_handle_irq(girq);
+		}
+
+	}
+
+	chained_irq_exit(ic, desc);
+}
+
+static struct irq_chip aspeed_sgpio_irqchip = {
+	.name       = "aspeed-sgpio",
+	.irq_ack    = aspeed_sgpio_irq_ack,
+	.irq_mask   = aspeed_sgpio_irq_mask,
+	.irq_unmask = aspeed_sgpio_irq_unmask,
+	.irq_set_type   = aspeed_sgpio_set_type,
+};
+
+static int aspeed_sgpio_setup_irqs(struct aspeed_sgpio *gpio,
+				   struct platform_device *pdev)
+{
+	int rc, i;
+	const struct aspeed_sgpio_bank *bank;
+
+	rc = platform_get_irq(pdev, 0);
+	if (rc < 0)
+		return rc;
+
+	gpio->irq = rc;
+
+	/* Disable IRQ and clear Interrupt status registers for all SPGIO Pins. */
+	for (i = 0; i < ARRAY_SIZE(aspeed_sgpio_banks); i++) {
+		bank =  &aspeed_sgpio_banks[i];
+		/* disable irq enable bits */
+		iowrite32(0x00000000, bank_reg(gpio, bank, reg_irq_enable));
+		/* clear status bits */
+		iowrite32(0xffffffff, bank_reg(gpio, bank, reg_irq_status));
+	}
+
+	rc = gpiochip_irqchip_add(&gpio->chip, &aspeed_sgpio_irqchip,
+				  0, handle_bad_irq, IRQ_TYPE_NONE);
+	if (rc) {
+		dev_info(&pdev->dev, "Could not add irqchip\n");
+		return rc;
+	}
+
+	gpiochip_set_chained_irqchip(&gpio->chip, &aspeed_sgpio_irqchip,
+				     gpio->irq, aspeed_sgpio_irq_handler);
+
+	/* set IRQ settings and Enable Interrupt */
+	for (i = 0; i < ARRAY_SIZE(aspeed_sgpio_banks); i++) {
+		bank = &aspeed_sgpio_banks[i];
+		/* set falling or level-low irq */
+		iowrite32(0x00000000, bank_reg(gpio, bank, reg_irq_type0));
+		/* trigger type is edge */
+		iowrite32(0x00000000, bank_reg(gpio, bank, reg_irq_type1));
+		/* dual edge trigger mode. */
+		iowrite32(0xffffffff, bank_reg(gpio, bank, reg_irq_type2));
+		/* enable irq */
+		iowrite32(0xffffffff, bank_reg(gpio, bank, reg_irq_enable));
+	}
+
+	return 0;
+}
+
+static const struct of_device_id aspeed_sgpio_of_table[] = {
+	{ .compatible = "aspeed,ast2400-sgpio" },
+	{ .compatible = "aspeed,ast2500-sgpio" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, aspeed_sgpio_of_table);
+
+static int __init aspeed_sgpio_probe(struct platform_device *pdev)
+{
+	struct aspeed_sgpio *gpio;
+	u32 nr_gpios, sgpio_freq, sgpio_clk_div;
+	int rc;
+	unsigned long apb_freq;
+
+	gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
+	if (!gpio)
+		return -ENOMEM;
+
+	gpio->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(gpio->base))
+		return PTR_ERR(gpio->base);
+
+	rc = of_property_read_u32(pdev->dev.of_node, "ngpios", &nr_gpios);
+	if (rc < 0) {
+		dev_err(&pdev->dev, "Could not read ngpios property\n");
+		return -EINVAL;
+	} else if (nr_gpios > MAX_NR_SGPIO) {
+		dev_err(&pdev->dev, "Number of GPIOs exceeds the maximum of %d: %d\n",
+			MAX_NR_SGPIO, nr_gpios);
+		return -EINVAL;
+	}
+
+	rc = of_property_read_u32(pdev->dev.of_node, "bus-frequency", &sgpio_freq);
+	if (rc < 0) {
+		dev_err(&pdev->dev, "Could not read bus-frequency property\n");
+		return -EINVAL;
+	}
+
+	gpio->pclk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(gpio->pclk)) {
+		dev_err(&pdev->dev, "devm_clk_get failed\n");
+		return PTR_ERR(gpio->pclk);
+	}
+
+	apb_freq = clk_get_rate(gpio->pclk);
+
+	/*
+	 * From the datasheet,
+	 *	SGPIO period = 1/PCLK * 2 * (GPIO254[31:16] + 1)
+	 *	period = 2 * (GPIO254[31:16] + 1) / PCLK
+	 *	frequency = 1 / (2 * (GPIO254[31:16] + 1) / PCLK)
+	 *	frequency = PCLK / (2 * (GPIO254[31:16] + 1))
+	 *	frequency * 2 * (GPIO254[31:16] + 1) = PCLK
+	 *	GPIO254[31:16] = PCLK / (frequency * 2) - 1
+	 */
+	if (sgpio_freq == 0)
+		return -EINVAL;
+
+	sgpio_clk_div = (apb_freq / (sgpio_freq * 2)) - 1;
+
+	if (sgpio_clk_div > (1 << 16) - 1)
+		return -EINVAL;
+
+	iowrite32(FIELD_PREP(ASPEED_SGPIO_CLK_DIV_MASK, sgpio_clk_div) |
+		  FIELD_PREP(ASPEED_SGPIO_PINS_MASK, (nr_gpios / 8)) |
+		  ASPEED_SGPIO_ENABLE,
+		  gpio->base + ASPEED_SGPIO_CTRL);
+
+	spin_lock_init(&gpio->lock);
+
+	gpio->chip.parent = &pdev->dev;
+	gpio->chip.ngpio = nr_gpios;
+	gpio->chip.direction_input = aspeed_sgpio_dir_in;
+	gpio->chip.direction_output = aspeed_sgpio_dir_out;
+	gpio->chip.get_direction = aspeed_sgpio_get_direction;
+	gpio->chip.request = NULL;
+	gpio->chip.free = NULL;
+	gpio->chip.get = aspeed_sgpio_get;
+	gpio->chip.set = aspeed_sgpio_set;
+	gpio->chip.set_config = NULL;
+	gpio->chip.label = dev_name(&pdev->dev);
+	gpio->chip.base = -1;
+
+	/* set all SGPIO pins as input (1). */
+	memset(gpio->dir_in, 0xff, sizeof(gpio->dir_in));
+
+	rc = devm_gpiochip_add_data(&pdev->dev, &gpio->chip, gpio);
+	if (rc < 0)
+		return rc;
+
+	return aspeed_sgpio_setup_irqs(gpio, pdev);
+}
+
+static struct platform_driver aspeed_sgpio_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = aspeed_sgpio_of_table,
+	},
+};
+
+module_platform_driver_probe(aspeed_sgpio_driver, aspeed_sgpio_probe);
+MODULE_DESCRIPTION("Aspeed Serial GPIO Driver");
+MODULE_LICENSE("GPL");
-- 
2.7.4

[v6 2/2] gpio: aspeed: Add SGPIO driver

[Hongwei Zhang]

Hello Linus,

Thanks for your detailed comments.

We just submitted a v6 of sgpio-aspeed.c, it includes the updates based on
your initial feedback:

1. fix a bug in aspeed_sgpio_dir_out()
2. some comments clean up.

Regards,
--Hongwei 

> From:	Linus Walleij <linus.walleij@linaro.org>
> Sent:	Sunday, July 28, 2019 7:38 PM
> To:	Hongwei Zhang
> Cc:	Andrew Jeffery; linux-gpio; Joel Stanley; linux-aspeed; Bartosz Golaszewski; linux-kernel; linux-
> arm-kernel
> Subject:	Re: [v5 2/2] gpio: aspeed: Add SGPIO driver
> 
> On Mon, Jul 22, 2019 at 10:37 PM Hongwei Zhang <hongweiz@ami.com> wrote:
> 
> > As you suspected it correctly, AST2500 utilizes all the 32 bits of the 
> > registers (data value, interrupt, etc...), such that using 8-bit bands 
> > [7:0]/[15:8]/23:16]/[31:24] of GPIO_200H for SGPIO_A/B/C/D .
> > so registering 10 gpiochip drivers separately will make code more 
> > complicated, for example gpio_200 register (data_value reg) has to be 
> > shared by 4 gpiochip instances, and the same is true for gpio204 
> > (interrupt reg), and other more registers.
> > So we would prefer to keeping current implementation.
> 
> OK this is a pretty good argument. My review assumed one 32-bit register was not shared between 
> banks but it is, I see.
> 
> The above situation can be managed by regmap, but that will just a different complexity so go with this 
> approach then.
> 
> Yours,
> Linus Walleij

[v5 2/2] gpio: aspeed: Add SGPIO driver

[Hongwei Zhang]

Add SGPIO driver support for Aspeed AST2500 SoC.

Signed-off-by: Hongwei Zhang <hongweiz@ami.com>
---
 drivers/gpio/sgpio-aspeed.c | 521 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 521 insertions(+)
 create mode 100644 drivers/gpio/sgpio-aspeed.c

diff --git a/drivers/gpio/sgpio-aspeed.c b/drivers/gpio/sgpio-aspeed.c
new file mode 100644
index 0000000..9a17b1a
--- /dev/null
+++ b/drivers/gpio/sgpio-aspeed.c
@@ -0,0 +1,521 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2019 American Megatrends International LLC.
+ *
+ * Author: Karthikeyan Mani <karthikeyanm@amiindia.co.in>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/gpio/driver.h>
+#include <linux/hashtable.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+
+#define MAX_NR_SGPIO			80
+
+#define ASPEED_SGPIO_CTRL		0x54
+
+#define ASPEED_SGPIO_PINS_MASK		GENMASK(9, 6)
+#define ASPEED_SGPIO_CLK_DIV_MASK	GENMASK(31, 16)
+#define ASPEED_SGPIO_ENABLE		BIT(0)
+
+struct aspeed_sgpio {
+	struct gpio_chip chip;
+	struct clk *pclk;
+	spinlock_t lock;
+	void __iomem *base;
+	uint32_t dir_in[3];
+	int irq;
+};
+
+struct aspeed_sgpio_bank {
+	uint16_t    val_regs;
+	uint16_t    rdata_reg;
+	uint16_t    irq_regs;
+	const char  names[4][3];
+};
+
+/*
+ * Note: The "value" register returns the input value when the GPIO is
+ *	 configured as an input.
+ *
+ *	 The "rdata" register returns the output value when the GPIO is
+ *	 configured as an output.
+ */
+static const struct aspeed_sgpio_bank aspeed_sgpio_banks[] = {
+	{
+		.val_regs = 0x0000,
+		.rdata_reg = 0x0070,
+		.irq_regs = 0x0004,
+		.names = { "A", "B", "C", "D" },
+	},
+	{
+		.val_regs = 0x001C,
+		.rdata_reg = 0x0074,
+		.irq_regs = 0x0020,
+		.names = { "E", "F", "G", "H" },
+	},
+	{
+		.val_regs = 0x0038,
+		.rdata_reg = 0x0078,
+		.irq_regs = 0x003C,
+		.names = { "I", "J" },
+	},
+};
+
+enum aspeed_sgpio_reg {
+	reg_val,
+	reg_rdata,
+	reg_irq_enable,
+	reg_irq_type0,
+	reg_irq_type1,
+	reg_irq_type2,
+	reg_irq_status,
+};
+
+#define GPIO_VAL_VALUE      0x00
+#define GPIO_IRQ_ENABLE     0x00
+#define GPIO_IRQ_TYPE0      0x04
+#define GPIO_IRQ_TYPE1      0x08
+#define GPIO_IRQ_TYPE2      0x0C
+#define GPIO_IRQ_STATUS     0x10
+
+static void __iomem *bank_reg(struct aspeed_sgpio *gpio,
+				     const struct aspeed_sgpio_bank *bank,
+				     const enum aspeed_sgpio_reg reg)
+{
+	switch (reg) {
+	case reg_val:
+		return gpio->base + bank->val_regs + GPIO_VAL_VALUE;
+	case reg_rdata:
+		return gpio->base + bank->rdata_reg;
+	case reg_irq_enable:
+		return gpio->base + bank->irq_regs + GPIO_IRQ_ENABLE;
+	case reg_irq_type0:
+		return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE0;
+	case reg_irq_type1:
+		return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE1;
+	case reg_irq_type2:
+		return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE2;
+	case reg_irq_status:
+		return gpio->base + bank->irq_regs + GPIO_IRQ_STATUS;
+	default:
+		/* acturally if code runs to here, it's an error case */
+		BUG_ON(1);
+	}
+}
+
+#define GPIO_BANK(x)    ((x) >> 5)
+#define GPIO_OFFSET(x)  ((x) & 0x1f)
+#define GPIO_BIT(x)     BIT(GPIO_OFFSET(x))
+
+static const struct aspeed_sgpio_bank *to_bank(unsigned int offset)
+{
+	unsigned int bank = GPIO_BANK(offset);
+
+	WARN_ON(bank >= ARRAY_SIZE(aspeed_sgpio_banks));
+	return &aspeed_sgpio_banks[bank];
+}
+
+static int aspeed_sgpio_get(struct gpio_chip *gc, unsigned int offset)
+{
+	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
+	const struct aspeed_sgpio_bank *bank = to_bank(offset);
+	unsigned long flags;
+	enum aspeed_sgpio_reg reg;
+	bool is_input;
+	int rc = 0;
+
+	spin_lock_irqsave(&gpio->lock, flags);
+
+	is_input = gpio->dir_in[GPIO_BANK(offset)] & GPIO_BIT(offset);
+	reg = is_input ? reg_val : reg_rdata;
+	rc = !!(ioread32(bank_reg(gpio, bank, reg)) & GPIO_BIT(offset));
+
+	spin_unlock_irqrestore(&gpio->lock, flags);
+
+	return rc;
+}
+
+static void aspeed_sgpio_set(struct gpio_chip *gc, unsigned int offset, int val)
+{
+	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
+	const struct aspeed_sgpio_bank *bank = to_bank(offset);
+	unsigned long flags;
+	void __iomem *addr;
+	u32 reg = 0;
+
+	spin_lock_irqsave(&gpio->lock, flags);
+
+	addr = bank_reg(gpio, bank, reg_val);
+
+	if (val)
+		reg |= GPIO_BIT(offset);
+	else
+		reg &= ~GPIO_BIT(offset);
+
+	iowrite32(reg, addr);
+
+	spin_unlock_irqrestore(&gpio->lock, flags);
+}
+
+static int aspeed_sgpio_dir_in(struct gpio_chip *gc, unsigned int offset)
+{
+	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&gpio->lock, flags);
+	gpio->dir_in[GPIO_BANK(offset)] |= GPIO_BIT(offset);
+	spin_unlock_irqrestore(&gpio->lock, flags);
+
+	return 0;
+}
+
+static int aspeed_sgpio_dir_out(struct gpio_chip *gc, unsigned int offset, int val)
+{
+	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&gpio->lock, flags);
+	gpio->dir_in[GPIO_BANK(offset)] &= ~GPIO_BIT(offset);
+	spin_unlock_irqrestore(&gpio->lock, flags);
+
+	aspeed_sgpio_set(gc, offset, val);
+
+	return 0;
+}
+
+static int aspeed_sgpio_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+	int dir_status;
+	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&gpio->lock, flags);
+	dir_status = gpio->dir_in[GPIO_BANK(offset)] & GPIO_BIT(offset);
+	spin_unlock_irqrestore(&gpio->lock, flags);
+
+	return dir_status;
+
+}
+
+static void irqd_to_aspeed_sgpio_data(struct irq_data *d,
+					     struct aspeed_sgpio **gpio,
+					     const struct aspeed_sgpio_bank **bank,
+					     u32 *bit, int *offset)
+{
+	struct aspeed_sgpio *internal;
+
+	*offset = irqd_to_hwirq(d);
+	internal = irq_data_get_irq_chip_data(d);
+	WARN_ON(!internal);
+
+	*gpio = internal;
+	*bank = to_bank(*offset);
+	*bit = GPIO_BIT(*offset);
+}
+
+static void aspeed_sgpio_irq_ack(struct irq_data *d)
+{
+	const struct aspeed_sgpio_bank *bank;
+	struct aspeed_sgpio *gpio;
+	unsigned long flags;
+	void __iomem *status_addr;
+	int offset;
+	u32 bit;
+
+	irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
+
+	status_addr = bank_reg(gpio, bank, reg_irq_status);
+
+	spin_lock_irqsave(&gpio->lock, flags);
+
+	iowrite32(bit, status_addr);
+
+	spin_unlock_irqrestore(&gpio->lock, flags);
+}
+
+static void aspeed_sgpio_irq_set_mask(struct irq_data *d, bool set)
+{
+	const struct aspeed_sgpio_bank *bank;
+	struct aspeed_sgpio *gpio;
+	unsigned long flags;
+	u32 reg, bit;
+	void __iomem *addr;
+	int offset;
+
+	irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
+	addr = bank_reg(gpio, bank, reg_irq_enable);
+
+	spin_lock_irqsave(&gpio->lock, flags);
+
+	reg = ioread32(addr);
+	if (set)
+		reg |= bit;
+	else
+		reg &= ~bit;
+
+	iowrite32(reg, addr);
+
+	spin_unlock_irqrestore(&gpio->lock, flags);
+}
+
+static void aspeed_sgpio_irq_mask(struct irq_data *d)
+{
+	aspeed_sgpio_irq_set_mask(d, false);
+}
+
+static void aspeed_sgpio_irq_unmask(struct irq_data *d)
+{
+	aspeed_sgpio_irq_set_mask(d, true);
+}
+
+static int aspeed_sgpio_set_type(struct irq_data *d, unsigned int type)
+{
+	u32 type0 = 0;
+	u32 type1 = 0;
+	u32 type2 = 0;
+	u32 bit, reg;
+	const struct aspeed_sgpio_bank *bank;
+	irq_flow_handler_t handler;
+	struct aspeed_sgpio *gpio;
+	unsigned long flags;
+	void __iomem *addr;
+	int offset;
+
+	irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
+
+	switch (type & IRQ_TYPE_SENSE_MASK) {
+	case IRQ_TYPE_EDGE_BOTH:
+		type2 |= bit;
+		/* fall through */
+	case IRQ_TYPE_EDGE_RISING:
+		type0 |= bit;
+		/* fall through */
+	case IRQ_TYPE_EDGE_FALLING:
+		handler = handle_edge_irq;
+		break;
+	case IRQ_TYPE_LEVEL_HIGH:
+		type0 |= bit;
+		/* fall through */
+	case IRQ_TYPE_LEVEL_LOW:
+		type1 |= bit;
+		handler = handle_level_irq;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&gpio->lock, flags);
+
+	addr = bank_reg(gpio, bank, reg_irq_type0);
+	reg = ioread32(addr);
+	reg = (reg & ~bit) | type0;
+	iowrite32(reg, addr);
+
+	addr = bank_reg(gpio, bank, reg_irq_type1);
+	reg = ioread32(addr);
+	reg = (reg & ~bit) | type1;
+	iowrite32(reg, addr);
+
+	addr = bank_reg(gpio, bank, reg_irq_type2);
+	reg = ioread32(addr);
+	reg = (reg & ~bit) | type2;
+	iowrite32(reg, addr);
+
+	spin_unlock_irqrestore(&gpio->lock, flags);
+
+	irq_set_handler_locked(d, handler);
+
+	return 0;
+}
+
+static void aspeed_sgpio_irq_handler(struct irq_desc *desc)
+{
+	struct gpio_chip *gc = irq_desc_get_handler_data(desc);
+	struct irq_chip *ic = irq_desc_get_chip(desc);
+	struct aspeed_sgpio *data = gpiochip_get_data(gc);
+	unsigned int i, p, girq;
+	unsigned long reg;
+
+	chained_irq_enter(ic, desc);
+
+	for (i = 0; i < ARRAY_SIZE(aspeed_sgpio_banks); i++) {
+		const struct aspeed_sgpio_bank *bank = &aspeed_sgpio_banks[i];
+
+		reg = ioread32(bank_reg(data, bank, reg_irq_status));
+
+		for_each_set_bit(p, &reg, 32) {
+			girq = irq_find_mapping(gc->irq.domain, i * 32 + p);
+			generic_handle_irq(girq);
+		}
+
+	}
+
+	chained_irq_exit(ic, desc);
+}
+
+static struct irq_chip aspeed_sgpio_irqchip = {
+	.name       = "aspeed-sgpio",
+	.irq_ack    = aspeed_sgpio_irq_ack,
+	.irq_mask   = aspeed_sgpio_irq_mask,
+	.irq_unmask = aspeed_sgpio_irq_unmask,
+	.irq_set_type   = aspeed_sgpio_set_type,
+};
+
+static int aspeed_sgpio_setup_irqs(struct aspeed_sgpio *gpio,
+				   struct platform_device *pdev)
+{
+	int rc, i;
+	const struct aspeed_sgpio_bank *bank;
+
+	rc = platform_get_irq(pdev, 0);
+	if (rc < 0)
+		return rc;
+
+	gpio->irq = rc;
+
+	/* Disable IRQ and clear Interrupt status registers for all SPGIO Pins. */
+	for (i = 0; i < ARRAY_SIZE(aspeed_sgpio_banks); i++) {
+		bank =  &aspeed_sgpio_banks[i];
+		/* disable irq enable bits */
+		iowrite32(0x00000000, bank_reg(gpio, bank, reg_irq_enable));
+		/* clear status bits */
+		iowrite32(0xffffffff, bank_reg(gpio, bank, reg_irq_status));
+	}
+
+	rc = gpiochip_irqchip_add(&gpio->chip, &aspeed_sgpio_irqchip,
+				  0, handle_bad_irq, IRQ_TYPE_NONE);
+	if (rc) {
+		dev_info(&pdev->dev, "Could not add irqchip\n");
+		return rc;
+	}
+
+	gpiochip_set_chained_irqchip(&gpio->chip, &aspeed_sgpio_irqchip,
+				     gpio->irq, aspeed_sgpio_irq_handler);
+
+	/* set IRQ settings and Enable Interrupt */
+	for (i = 0; i < ARRAY_SIZE(aspeed_sgpio_banks); i++) {
+		bank = &aspeed_sgpio_banks[i];
+		/* set falling or level-low irq */
+		iowrite32(0x00000000, bank_reg(gpio, bank, reg_irq_type0));
+		/* trigger type is edge */
+		iowrite32(0x00000000, bank_reg(gpio, bank, reg_irq_type1));
+		/* dual edge trigger mode. */
+		iowrite32(0xffffffff, bank_reg(gpio, bank, reg_irq_type2));
+		/* enable irq */
+		iowrite32(0xffffffff, bank_reg(gpio, bank, reg_irq_enable));
+	}
+
+	return 0;
+}
+
+static const struct of_device_id aspeed_sgpio_of_table[] = {
+	{ .compatible = "aspeed,ast2400-sgpio" },
+	{ .compatible = "aspeed,ast2500-sgpio" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, aspeed_sgpio_of_table);
+
+static int __init aspeed_sgpio_probe(struct platform_device *pdev)
+{
+	struct aspeed_sgpio *gpio;
+	u32 nr_gpios, sgpio_freq, sgpio_clk_div;
+	int rc;
+	unsigned long apb_freq;
+
+	gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
+	if (!gpio)
+		return -ENOMEM;
+
+	gpio->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(gpio->base))
+		return PTR_ERR(gpio->base);
+
+	rc = of_property_read_u32(pdev->dev.of_node, "ngpios", &nr_gpios);
+	if (rc < 0) {
+		dev_err(&pdev->dev, "Could not read ngpios property\n");
+		return -EINVAL;
+	} else if (nr_gpios > MAX_NR_SGPIO) {
+		dev_err(&pdev->dev, "Number of GPIOs exceeds the maximum of %d: %d\n",
+			MAX_NR_SGPIO, nr_gpios);
+		return -EINVAL;
+	}
+
+	rc = of_property_read_u32(pdev->dev.of_node, "bus-frequency", &sgpio_freq);
+	if (rc < 0) {
+		dev_err(&pdev->dev, "Could not read bus-frequency property\n");
+		return -EINVAL;
+	}
+
+	gpio->pclk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(gpio->pclk)) {
+		dev_err(&pdev->dev, "devm_clk_get failed\n");
+		return PTR_ERR(gpio->pclk);
+	}
+
+	apb_freq = clk_get_rate(gpio->pclk);
+
+	/*
+	 * From the datasheet,
+	 *	SGPIO period = 1/PCLK * 2 * (GPIO254[31:16] + 1)
+	 *	period = 2 * (GPIO254[31:16] + 1) / PCLK
+	 *	frequency = 1 / (2 * (GPIO254[31:16] + 1) / PCLK)
+	 *	frequency = PCLK / (2 * (GPIO254[31:16] + 1))
+	 *	frequency * 2 * (GPIO254[31:16] + 1) = PCLK
+	 *	GPIO254[31:16] = PCLK / (frequency * 2) - 1
+	 */
+	if (sgpio_freq == 0)
+		return -EINVAL;
+
+	sgpio_clk_div = (apb_freq / (sgpio_freq * 2)) - 1;
+
+	if (sgpio_clk_div > (1 << 16) - 1)
+		return -EINVAL;
+
+	iowrite32(FIELD_PREP(ASPEED_SGPIO_CLK_DIV_MASK, sgpio_clk_div) |
+		  FIELD_PREP(ASPEED_SGPIO_PINS_MASK, (nr_gpios / 8)) |
+		  ASPEED_SGPIO_ENABLE,
+		  gpio->base + ASPEED_SGPIO_CTRL);
+
+	spin_lock_init(&gpio->lock);
+
+	gpio->chip.parent = &pdev->dev;
+	gpio->chip.ngpio = nr_gpios;
+	gpio->chip.direction_input = aspeed_sgpio_dir_in;
+	gpio->chip.direction_output = aspeed_sgpio_dir_out;
+	gpio->chip.get_direction = aspeed_sgpio_get_direction;
+	gpio->chip.request = NULL;
+	gpio->chip.free = NULL;
+	gpio->chip.get = aspeed_sgpio_get;
+	gpio->chip.set = aspeed_sgpio_set;
+	gpio->chip.set_config = NULL;
+	gpio->chip.label = dev_name(&pdev->dev);
+	gpio->chip.base = -1;
+
+	/* set all SGPIO pins as input (1). */
+	memset(gpio->dir_in, 0xff, sizeof(gpio->dir_in));
+
+	rc = devm_gpiochip_add_data(&pdev->dev, &gpio->chip, gpio);
+	if (rc < 0)
+		return rc;
+
+	return aspeed_sgpio_setup_irqs(gpio, pdev);
+}
+
+static struct platform_driver aspeed_sgpio_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = aspeed_sgpio_of_table,
+	},
+};
+
+module_platform_driver_probe(aspeed_sgpio_driver, aspeed_sgpio_probe);
+MODULE_DESCRIPTION("Aspeed Serial GPIO Driver");
+MODULE_LICENSE("GPL");
-- 
2.7.4