Message-Id: <ce557bcd-6719-4138-a90f-3c8a27fa1199@www.fastmail.com>
Date:   Wed, 31 Jul 2019 09:49:21 +0930
From:   "Andrew Jeffery" <andrew@...id.au>
To:     "Hongwei Zhang" <hongweiz@....com>,
        "Linus Walleij" <linus.walleij@...aro.org>,
        linux-gpio@...r.kernel.org
Cc:     "Joel Stanley" <joel@....id.au>, linux-aspeed@...ts.ozlabs.org,
        "Bartosz Golaszewski" <bgolaszewski@...libre.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [v6 2/2] gpio: aspeed: Add SGPIO driver



On Wed, 31 Jul 2019, at 00:55, Hongwei Zhang wrote:
> Add SGPIO driver support for Aspeed AST2500 SoC.
> 
> Signed-off-by: Hongwei Zhang <hongweiz@....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-or-later
> +/*
> + * Copyright 2019 American Megatrends International LLC.
> + *
> + * Author: Karthikeyan Mani <karthikeyanm@...india.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);

reg is zero-initialised above and you haven't read from addr to assign to reg, so
the else branch is redundant (reg is already zeroed). This path has a bug - you're
clearing the state of all GPIOs associated with addr rather than just the GPIO
associated with 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);

In this case you should probably have an unlocked variant of aspeed_sgpio_set()
so you can call it inside the the critical section above instead of needing to
acquire/release the lock twice (once above and again in aspeed_sgpio_set()
as it stands).

Cheers,

Andrew

> +
> +	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
> 
>

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