Re: [PATCH 2/3 linux,dev-5.1 v1] ARM: dts: aspeed: Add SGPIO driver

["Andrew Jeffery" <andrew@xxxxxxxx>]

Hello Hongwei,

As this is patch is sent to the upstream lists (linux-gpio@ etc) please
drop the OpenBMC-specific "linux,dev-5.1" from the subject.

Also, it looks like you may have manually added the series revision (v1).
For the record you can make `git format-patch` do this for you with the
`-v`option (e.g. if you really want it here, `-v 1`).

On Thu, 4 Jul 2019, at 07:09, Hongwei Zhang wrote:
> Add SGPIO driver support for Aspeed AST2500 SoC.
> 
> Signed-off-by: Hongwei Zhang <hongweiz@xxxxxxx>
> ---
>  drivers/gpio/sgpio-aspeed.c | 470 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 470 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..108ed13
> --- /dev/null
> +++ b/drivers/gpio/sgpio-aspeed.c
> @@ -0,0 +1,470 @@
> +/*
> + * Copyright 2019 American Megatrends International LLC. 
> + *  
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.

You should use the SPDX license identifier here rather than the GPL
blurb, and it should be the first line of the file. Keep your copyright
line in place though:

// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright 2019 American Megatrends International LLC.

> + */
> +
> +#include <linux/gpio/driver.h>
> +#include <linux/gpio/aspeed.h>
> +#include <linux/hashtable.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/pinctrl/consumer.h>
> +#include <linux/platform_device.h>
> +#include <linux/spinlock.h>
> +#include <linux/string.h>
> +
> +#define NR_SGPIO        80
> +
> +struct aspeed_sgpio {
> +	struct gpio_chip chip;
> +	spinlock_t lock;
> +	void __iomem *base;
> +	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 sampled on the
> + *       line even when the GPIO is configured as an output. Since
> + *       that input goes through synchronizers, writing, then reading
> + *       back may not return the written value right away.
> + *
> + *       The "rdata" register returns the content of the write latch
> + *       and thus can be used to read back what was last written
> + *       reliably.
> + */
> +
> +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_VAL_DIR        0x04
> +#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
> +
> +/* This will be resolved at compile time */
> +static inline 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;
> +	}
> +	BUG_ON(1);

This isn't appropriate - we shouldn't take down the kernel on a
faulty peripheral access. Please change this to WARN().

> +}
> +
> +#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 inline bool have_gpio(struct aspeed_sgpio *gpio, unsigned int 
> offset)
> +{
> +	const struct aspeed_sgpio_bank *bank = to_bank(offset);
> +	unsigned int group = GPIO_OFFSET(offset) / 8;
> +
> +	return bank->names[group][0] != '\0';

Lets just drop have_gpio() altogether, it's a contiguous set of 80 GPIOs.
At best this should just be:

static inline bool have_gpio(struct aspeed_sgpio *gpio, unsigned int offset)
{
    return offset < NR_SGPIO;
}

But lets just assume that we've properly configured the gpio subsystem
for the controller and remove it completely.

> +}
> +
> +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);
> +
> +	return !!(ioread32(bank_reg(gpio, bank, reg_val)) & GPIO_BIT(offset));
> +}
> +
> +static void __aspeed_sgpio_set(struct gpio_chip *gc, unsigned int 
> offset,
> +			       int val)

No need to split this out from aspeed_sgpio_set() below. Separating
the implementation was necessary in the parallel GPIO driver for reasons
that aren't relevant here.

> +{
> +	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
> +	const struct aspeed_sgpio_bank *bank = to_bank(offset);
> +	void __iomem *addr;
> +	u32 reg;
> +
> +	addr = bank_reg(gpio, bank, reg_val);
> +
> +	if (val)
> +		reg |= GPIO_BIT(offset);
> +	else
> +		reg &= ~GPIO_BIT(offset);
> +
> +	iowrite32(reg, addr);
> +}
> +
> +static void aspeed_sgpio_set(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);
> +
> +	__aspeed_sgpio_set(gc, offset, val);
> +
> +	spin_unlock_irqrestore(&gpio->lock, flags);
> +}
> +
> +static int aspeed_sgpio_dir_in(struct gpio_chip *gc, unsigned int 
> offset)
> +{
> +	/* By default all SGPIO Pins are input */

Right, but with your implementation below you can never mark them as
output.

> +	return 0;
> +}
> +
> +static int aspeed_sgpio_get_direction(struct gpio_chip *gc, unsigned 
> int offset)
> +{
> +	/* By default all SGPIO Pins are input */
> +	return 1;

As above. Given my understanding of SGPIO, I think you should be
implementing both dir_in() and dir_out(), and capturing which state
userspace "wants" the GPIO to be in, and directing reads/writes to the
DATA_READ/DATA_VALUE registers as appropriate. There's no state
we need to modify in the hardware, but that doesn't mean we shouldn't
capture the intent of userspace at all.

> +
> +}
> +
> +static inline int 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);
> +
> +	*gpio = internal;
> +	*bank = to_bank(*offset);
> +	*bit = GPIO_BIT(*offset);
> +
> +	return 0;
> +}
> +
> +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 rc, offset;
> +	u32 bit;
> +
> +	rc = irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
> +	if (rc)
> +		return;
> +
> +	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 rc, offset;
> +
> +	rc = irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
> +	if (rc)
> +		return;
> +
> +	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 rc, offset;
> +
> +	rc = irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
> +	if (rc)
> +		return -EINVAL;
> +
> +	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 int aspeed_sgpio_request(struct gpio_chip *chip, unsigned int 
> offset)
> +{
> +	if (!have_gpio(gpiochip_get_data(chip), offset))
> +		return -ENODEV;
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id aspeed_sgpio_of_table[] = {
> +	{ .compatible = "aspeed,ast2400-sgpio", .data = NULL, },
> +	{ .compatible = "aspeed,ast2500-sgpio", .data = NULL,},

You can drop the assignment to data.

> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, aspeed_sgpio_of_table);
> +
> +static int __init aspeed_sgpio_probe(struct platform_device *pdev)
> +{
> +	const struct of_device_id *gpio_id;
> +	struct aspeed_sgpio *gpio;
> +	struct resource *res;
> +	int rc, i;
> +
> +	gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
> +	if (!gpio)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	gpio->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(gpio->base))
> +		return PTR_ERR(gpio->base);
> +
> +	spin_lock_init(&gpio->lock);
> +
> +	gpio_id = of_match_node(aspeed_sgpio_of_table, pdev->dev.of_node);
> +	if (!gpio_id)
> +		return -EINVAL;

gpio_id isn't used, so you can drop the of_match_node() above.

> +
> +	gpio->chip.parent = &pdev->dev;
> +	gpio->chip.ngpio = NR_SGPIO;
> +	gpio->chip.direction_input = aspeed_sgpio_dir_in;
> +	gpio->chip.direction_output = NULL;

We can do outputs too - we shouldn't be omitting the direction_output
callback, see the discussion above about dir_in()/dir_out()/get_direction()

Andrew

> +	gpio->chip.get_direction = aspeed_sgpio_get_direction;
> +	gpio->chip.request = aspeed_sgpio_request;
> +	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;
> +
> +	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
> 
>