Message-ID: <20210527023455.GA9971@aspeedtech.com>
Date:   Thu, 27 May 2021 10:34:56 +0800
From:   Steven Lee <steven_lee@...eedtech.com>
To:     Andrew Jeffery <andrew@...id.au>
CC:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Joel Stanley <joel@....id.au>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "moderated list:ARM/ASPEED MACHINE SUPPORT" 
        <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/ASPEED MACHINE SUPPORT" 
        <linux-aspeed@...ts.ozlabs.org>,
        open list <linux-kernel@...r.kernel.org>,
        Hongwei Zhang <Hongweiz@....com>,
        Ryan Chen <ryan_chen@...eedtech.com>,
        Billy Tsai <billy_tsai@...eedtech.com>,
        "Jeremy Kerr" <jk@...econstruct.com.au>
Subject: Re: [PATCH v1 4/4] gpio: gpio-aspeed-sgpio: Add AST2600 sgpio support

The 05/27/2021 09:26, Andrew Jeffery wrote:
> Hi Steven,
> 
> On Wed, 26 May 2021, at 19:16, Steven Lee wrote:
> > AST2600 SoC has 2 SGPIO master interfaces one with 128 pins another one
> > with 80 pins, and AST2500/AST2400 SoC has 1 SGPIO master interface that
> > supports up to 80 pins.
> > In the current driver design, the max number of sgpio pins is hardcoded
> > in macro MAX_NR_HW_SGPIO and the value is 80.
> > The patch makes the maximum gpio number *constraint of chip* comes from
> > the dts. The property name is max-ngpios.
> > 
> > Signed-off-by: Steven Lee <steven_lee@...eedtech.com>
> > ---
> >  drivers/gpio/gpio-aspeed-sgpio.c | 193 ++++++++++++++++++++-----------
> >  1 file changed, 125 insertions(+), 68 deletions(-)
> > 
> > diff --git a/drivers/gpio/gpio-aspeed-sgpio.c b/drivers/gpio/gpio-aspeed-sgpio.c
> > index 64e54f8c30d2..f74bd7988b66 100644
> > --- a/drivers/gpio/gpio-aspeed-sgpio.c
> > +++ b/drivers/gpio/gpio-aspeed-sgpio.c
> > @@ -17,37 +17,28 @@
> >  #include <linux/spinlock.h>
> >  #include <linux/string.h>
> >  
> > -/*
> > - * MAX_NR_HW_GPIO represents the number of actual hardware-supported GPIOs (ie,
> > - * slots within the clocked serial GPIO data). Since each HW GPIO is both an
> > - * input and an output, we provide MAX_NR_HW_GPIO * 2 lines on our gpiochip
> > - * device.
> > - *
> > - * We use SGPIO_OUTPUT_OFFSET to define the split between the inputs and
> > - * outputs; the inputs start at line 0, the outputs start at OUTPUT_OFFSET.
> > - */
> > -#define MAX_NR_HW_SGPIO			80
> > -#define SGPIO_OUTPUT_OFFSET		MAX_NR_HW_SGPIO
> 
> I expect you want to keep these as fall-back values for old devicetrees 
> that don't have your new properties.
> 

I will add them back as fall-back values.

> > -
> >  #define ASPEED_SGPIO_CTRL		0x54
> >  
> > -#define ASPEED_SGPIO_PINS_MASK		GENMASK(9, 6)
> > +#define ASPEED_SGPIO_PINS_MASK		GENMASK(10, 6)
> 
> Is this valid on the 2400 and 2500? This might be better defined in 
> platform data so we don't go writing reserved bits on older hardware?
> 

I will add them in platform data.
> >  #define ASPEED_SGPIO_CLK_DIV_MASK	GENMASK(31, 16)
> >  #define ASPEED_SGPIO_ENABLE		BIT(0)
> >  
> >  struct aspeed_sgpio {
> >  	struct gpio_chip chip;
> > +	struct irq_chip intc;
> 
> My gut instinct is this could be in a separate patch.
> 

I will move irq releated modification to a separate patch.
> >  	struct clk *pclk;
> >  	spinlock_t lock;
> >  	void __iomem *base;
> >  	int irq;
> > +	int max_ngpios;
> >  	int n_sgpio;
> >  };
> >  
> >  struct aspeed_sgpio_bank {
> > -	uint16_t    val_regs;
> > -	uint16_t    rdata_reg;
> > -	uint16_t    irq_regs;
> > +	u16    val_regs;
> > +	u16    rdata_reg;
> > +	u16    irq_regs;
> > +	u16    tolerance_regs;
> 
> I suggest splitting this out into a cleanup patch.
> 

Will do it.
> >  	const char  names[4][3];
> >  };
> >  
> > @@ -63,19 +54,29 @@ static const struct aspeed_sgpio_bank 
> > aspeed_sgpio_banks[] = {
> >  		.val_regs = 0x0000,
> >  		.rdata_reg = 0x0070,
> >  		.irq_regs = 0x0004,
> > +		.tolerance_regs = 0x0018,
> 
> Reset tolerance is supported on the 2500. Your patch subject claims its 
> for supporting the 2600, so I think the addition of reset tolerance 
> capabilities should be a separate patch.
> 
> By splitting out the different patches as requested, I think this patch 
> can just become about supporting max_ngpios, which will help focus the 
> discussion.
> 

Ok, I will separate max_ngpios, irq_chip and tolerance_reg to 3 patches
in V3.

> >  		.names = { "A", "B", "C", "D" },
> >  	},
> >  	{
> >  		.val_regs = 0x001C,
> >  		.rdata_reg = 0x0074,
> >  		.irq_regs = 0x0020,
> > +		.tolerance_regs = 0x0034,
> >  		.names = { "E", "F", "G", "H" },
> >  	},
> >  	{
> >  		.val_regs = 0x0038,
> >  		.rdata_reg = 0x0078,
> >  		.irq_regs = 0x003C,
> > -		.names = { "I", "J" },
> > +		.tolerance_regs = 0x0050,
> > +		.names = { "I", "J", "K", "L" },
> > +	},
> > +	{
> > +		.val_regs = 0x0090,
> > +		.rdata_reg = 0x007C,
> > +		.irq_regs = 0x0094,
> > +		.tolerance_regs = 0x00A8,
> > +		.names = { "M", "N", "O", "P" },
> >  	},
> >  };
> >  
> > @@ -87,14 +88,14 @@ enum aspeed_sgpio_reg {
> >  	reg_irq_type1,
> >  	reg_irq_type2,
> >  	reg_irq_status,
> > +	reg_tolerance,
> >  };
> >  
> > -#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
> > +#define GPIO_IRQ_OFFSET_ENABLE     0x00
> > +#define GPIO_IRQ_OFFSET_TYPE0      0x04
> > +#define GPIO_IRQ_OFFSET_TYPE1      0x08
> > +#define GPIO_IRQ_OFFSET_TYPE2      0x0C
> > +#define GPIO_IRQ_OFFSET_STATUS     0x10
> 
> I don't think this change is necessary. It looks like it produces a 
> bunch of noise in the diff.
> 

Thanks, I will use the original naming.

> >  
> >  static void __iomem *bank_reg(struct aspeed_sgpio *gpio,
> >  				     const struct aspeed_sgpio_bank *bank,
> > @@ -102,34 +103,37 @@ static void __iomem *bank_reg(struct aspeed_sgpio *gpio,
> >  {
> >  	switch (reg) {
> >  	case reg_val:
> > -		return gpio->base + bank->val_regs + GPIO_VAL_VALUE;
> > +		return gpio->base + bank->val_regs;
> >  	case reg_rdata:
> >  		return gpio->base + bank->rdata_reg;
> >  	case reg_irq_enable:
> > -		return gpio->base + bank->irq_regs + GPIO_IRQ_ENABLE;
> > +		return gpio->base + bank->irq_regs + GPIO_IRQ_OFFSET_ENABLE;
> >  	case reg_irq_type0:
> > -		return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE0;
> > +		return gpio->base + bank->irq_regs + GPIO_IRQ_OFFSET_TYPE0;
> >  	case reg_irq_type1:
> > -		return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE1;
> > +		return gpio->base + bank->irq_regs + GPIO_IRQ_OFFSET_TYPE1;
> >  	case reg_irq_type2:
> > -		return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE2;
> > +		return gpio->base + bank->irq_regs + GPIO_IRQ_OFFSET_TYPE2;
> >  	case reg_irq_status:
> > -		return gpio->base + bank->irq_regs + GPIO_IRQ_STATUS;
> > +		return gpio->base + bank->irq_regs + GPIO_IRQ_OFFSET_STATUS;
> > +	case reg_tolerance:
> > +		return gpio->base + bank->tolerance_regs;
> >  	default:
> >  		/* acturally if code runs to here, it's an error case */
> >  		BUG();
> >  	}
> >  }
> >  
> > -#define GPIO_BANK(x)    ((x % SGPIO_OUTPUT_OFFSET) >> 5)
> > -#define GPIO_OFFSET(x)  ((x % SGPIO_OUTPUT_OFFSET) & 0x1f)
> > +#define GPIO_BANK(x)    ((x) >> 5)
> > +/* modulo 32 */
> > +#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)
> > +static const struct aspeed_sgpio_bank *to_bank(unsigned int offset, 
> > unsigned int max_ngpios)
> >  {
> >  	unsigned int bank;
> >  
> > -	bank = GPIO_BANK(offset);
> > +	bank = GPIO_BANK(offset % max_ngpios);
> >  
> >  	WARN_ON(bank >= ARRAY_SIZE(aspeed_sgpio_banks));
> >  	return &aspeed_sgpio_banks[bank];
> > @@ -139,18 +143,19 @@ static int aspeed_sgpio_init_valid_mask(struct 
> > gpio_chip *gc,
> >  		unsigned long *valid_mask, unsigned int ngpios)
> >  {
> >  	struct aspeed_sgpio *sgpio = gpiochip_get_data(gc);
> > +	int max_ngpios = sgpio->max_ngpios;
> >  	int n = sgpio->n_sgpio;
> > -	int c = SGPIO_OUTPUT_OFFSET - n;
> > +	int c = max_ngpios - n;
> >  
> > -	WARN_ON(ngpios < MAX_NR_HW_SGPIO * 2);
> > +	WARN_ON(ngpios < max_ngpios * 2);
> >  
> >  	/* input GPIOs in the lower range */
> >  	bitmap_set(valid_mask, 0, n);
> >  	bitmap_clear(valid_mask, n, c);
> >  
> > -	/* output GPIOS above SGPIO_OUTPUT_OFFSET */
> > -	bitmap_set(valid_mask, SGPIO_OUTPUT_OFFSET, n);
> > -	bitmap_clear(valid_mask, SGPIO_OUTPUT_OFFSET + n, c);
> > +	/* output GPIOS above max_ngpios */
> > +	bitmap_set(valid_mask, max_ngpios, n);
> > +	bitmap_clear(valid_mask, max_ngpios + n, c);
> >  
> >  	return 0;
> >  }
> > @@ -161,30 +166,30 @@ static void 
> > aspeed_sgpio_irq_init_valid_mask(struct gpio_chip *gc,
> >  	struct aspeed_sgpio *sgpio = gpiochip_get_data(gc);
> >  	int n = sgpio->n_sgpio;
> >  
> > -	WARN_ON(ngpios < MAX_NR_HW_SGPIO * 2);
> > +	WARN_ON(ngpios < sgpio->max_ngpios * 2);
> >  
> >  	/* input GPIOs in the lower range */
> >  	bitmap_set(valid_mask, 0, n);
> >  	bitmap_clear(valid_mask, n, ngpios - n);
> >  }
> >  
> > -static bool aspeed_sgpio_is_input(unsigned int offset)
> > +static bool aspeed_sgpio_is_input(unsigned int offset, unsigned int max_ngpios)
> >  {
> > -	return offset < SGPIO_OUTPUT_OFFSET;
> > +	return offset < max_ngpios;
> >  }
> >  
> >  static int aspeed_sgpio_get(struct gpio_chip *gc, unsigned int offset)
> >  {
> > +	const struct aspeed_sgpio_bank *bank = to_bank(offset, gpio->max_ngpios);
> 
> This references gpio before it's defined, as the build bot noted.
> 

Sorry for that, I've sent v2 patch for this issue.

> >  	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;
> >  	int rc = 0;
> >  
> >  	spin_lock_irqsave(&gpio->lock, flags);
> >  
> > -	reg = aspeed_sgpio_is_input(offset) ? reg_val : reg_rdata;
> > -	rc = !!(ioread32(bank_reg(gpio, bank, reg)) & GPIO_BIT(offset));
> > +	reg = aspeed_sgpio_is_input(offset, gpio->max_ngpios) ? reg_val : 
> > reg_rdata;
> 
> We should just pass gpio here (i.e. make aspeed_sgpio_is_input take a 
> 'const struct aspeed_sgpio *' parameter), rather than open-coding 
> gpio->max_ngpios. This approach will make it easier to refactor the 
> implementation in the future (if necessary).
> 

I will rewrite the function to use aspeed_sgpio struct.

> > +	rc = !!(ioread32(bank_reg(gpio, bank, reg)) & GPIO_BIT(offset % 
> > gpio->max_ngpios));
> >  
> >  	spin_unlock_irqrestore(&gpio->lock, flags);
> >  
> > @@ -193,12 +198,12 @@ static int aspeed_sgpio_get(struct gpio_chip *gc, 
> > unsigned int offset)
> >  
> >  static int sgpio_set_value(struct gpio_chip *gc, unsigned int offset, int val)
> >  {
> > +	const struct aspeed_sgpio_bank *bank = to_bank(offset, gpio->max_ngpios);
> 
> References gpio before it's defined.
> 

Fixed in V2.

> >  	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
> > -	const struct aspeed_sgpio_bank *bank = to_bank(offset);
> >  	void __iomem *addr_r, *addr_w;
> >  	u32 reg = 0;
> >  
> > -	if (aspeed_sgpio_is_input(offset))
> > +	if (aspeed_sgpio_is_input(offset, gpio->max_ngpios))
> >  		return -EINVAL;
> >  
> >  	/* Since this is an output, read the cached value from rdata, then
> > @@ -209,9 +214,9 @@ static int sgpio_set_value(struct gpio_chip *gc, 
> > unsigned int offset, int val)
> >  	reg = ioread32(addr_r);
> >  
> >  	if (val)
> > -		reg |= GPIO_BIT(offset);
> > +		reg |= GPIO_BIT(offset % gpio->max_ngpios);
> 
> Pass gpio through GPIO_BIT() too.
> 

I don't understand this comment.
Could you describe more?
Thanks.

> >  	else
> > -		reg &= ~GPIO_BIT(offset);
> > +		reg &= ~GPIO_BIT(offset % gpio->max_ngpios);
> >  
> >  	iowrite32(reg, addr_w);
> >  
> > @@ -232,7 +237,9 @@ static void aspeed_sgpio_set(struct gpio_chip *gc, 
> > unsigned int offset, int val)
> >  
> >  static int aspeed_sgpio_dir_in(struct gpio_chip *gc, unsigned int offset)
> >  {
> > -	return aspeed_sgpio_is_input(offset) ? 0 : -EINVAL;
> > +	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
> > +
> > +	return aspeed_sgpio_is_input(offset, gpio->max_ngpios) ? 0 : -EINVAL;
> >  }
> >  
> >  static int aspeed_sgpio_dir_out(struct gpio_chip *gc, unsigned int 
> > offset, int val)
> > @@ -253,7 +260,9 @@ static int aspeed_sgpio_dir_out(struct gpio_chip 
> > *gc, unsigned int offset, int v
> >  
> >  static int aspeed_sgpio_get_direction(struct gpio_chip *gc, unsigned 
> > int offset)
> >  {
> > -	return !!aspeed_sgpio_is_input(offset);
> > +	struct aspeed_sgpio *gpio = gpiochip_get_data(gc);
> > +
> > +	return !!aspeed_sgpio_is_input(offset, gpio->max_ngpios);
> >  }
> >  
> >  static void irqd_to_aspeed_sgpio_data(struct irq_data *d,
> > @@ -268,8 +277,8 @@ static void irqd_to_aspeed_sgpio_data(struct irq_data *d,
> >  	WARN_ON(!internal);
> >  
> >  	*gpio = internal;
> > -	*bank = to_bank(*offset);
> > -	*bit = GPIO_BIT(*offset);
> > +	*bank = to_bank(*offset, internal->max_ngpios);
> 
> Make to_bank take a 'const struct aspeed_sgpio *'.
> 

Will modify it.

> > +	*bit = GPIO_BIT(*offset % internal->max_ngpios);
> >  }
> >  
> >  static void aspeed_sgpio_irq_ack(struct irq_data *d)
> > @@ -412,14 +421,6 @@ static void aspeed_sgpio_irq_handler(struct irq_desc *desc)
> >  	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)
> >  {
> > @@ -442,8 +443,14 @@ static int aspeed_sgpio_setup_irqs(struct 
> > aspeed_sgpio *gpio,
> >  		iowrite32(0xffffffff, bank_reg(gpio, bank, reg_irq_status));
> >  	}
> >  
> > +	gpio->intc.name = dev_name(&pdev->dev);
> > +	gpio->intc.irq_ack = aspeed_sgpio_irq_ack;
> > +	gpio->intc.irq_mask = aspeed_sgpio_irq_mask;
> > +	gpio->intc.irq_unmask = aspeed_sgpio_irq_unmask;
> > +	gpio->intc.irq_set_type = aspeed_sgpio_set_type;
> > +
> >  	irq = &gpio->chip.irq;
> > -	irq->chip = &aspeed_sgpio_irqchip;
> > +	irq->chip = &gpio->intc;
> 
> As I said earlier, I think it would be best to split the IRQ changes 
> out into a separate patch ordered before this one.
> 

Will separate irq changes to another patch.

> >  	irq->init_valid_mask = aspeed_sgpio_irq_init_valid_mask;
> >  	irq->handler = handle_bad_irq;
> >  	irq->default_type = IRQ_TYPE_NONE;
> > @@ -466,9 +473,48 @@ static int aspeed_sgpio_setup_irqs(struct 
> > aspeed_sgpio *gpio,
> >  	return 0;
> >  }
> >  
> > +static int aspeed_sgpio_reset_tolerance(struct gpio_chip *chip,
> > +					unsigned int offset, bool enable)
> > +{
> > +	struct aspeed_sgpio *gpio = gpiochip_get_data(chip);
> > +	unsigned long flags;
> > +	void __iomem *reg;
> > +	u32 val;
> > +
> > +	reg = bank_reg(gpio, to_bank(offset, gpio->max_ngpios), reg_tolerance);
> > +
> > +	spin_lock_irqsave(&gpio->lock, flags);
> > +
> > +	val = readl(reg);
> > +
> > +	if (enable)
> > +		val |= GPIO_BIT(offset % gpio->max_ngpios);
> > +	else
> > +		val &= ~GPIO_BIT(offset % gpio->max_ngpios);
> > +
> > +	writel(val, reg);
> > +
> > +	spin_unlock_irqrestore(&gpio->lock, flags);
> > +
> > +	return 0;
> > +}
> > +
> > +static int aspeed_sgpio_set_config(struct gpio_chip *chip, unsigned int offset,
> > +				   unsigned long config)
> > +{
> > +	unsigned long param = pinconf_to_config_param(config);
> > +	u32 arg = pinconf_to_config_argument(config);
> > +
> > +	if (param == PIN_CONFIG_PERSIST_STATE)
> > +		return aspeed_sgpio_reset_tolerance(chip, offset, arg);
> > +	else
> > +		return -EOPNOTSUPP;
> > +}
> > +
> 
> Again, lets split reset tolerance out to a separate patch as well.
> 

Will separate tolerance to another patch.

> >  static const struct of_device_id aspeed_sgpio_of_table[] = {
> > -	{ .compatible = "aspeed,ast2400-sgpio" },
> > -	{ .compatible = "aspeed,ast2500-sgpio" },
> > +	{ .compatible = "aspeed,ast2400-sgpiom" },
> > +	{ .compatible = "aspeed,ast2500-sgpiom" },
> > +	{ .compatible = "aspeed,ast2600-sgpiom" },
> 
> No. You'll need to support both while we transition between the two as 
> the devicetree patch and the driver patch are separate, and this will 
> break bisectability when tracking down runtime issues. Also, the 
> devicetree patch should be ordered after the driver change for the same 
> reason.
> 
> You should continue to support the 'aspeed,ast2{4,5}00-sgpio' style 
> compatible here to handle old devicetrees.
> 
> So in summary, just add the 'aspeed,ast2{4,5,6}00-sgpiom' compatibles 
> for now, don't remove the 'aspeed,ast2{4,5}00-sgpio' compatibles.
> 

I will keep the original implementation and just add ast2600 compatible.

> >  	{}
> >  };
> >  
> > @@ -476,8 +522,8 @@ MODULE_DEVICE_TABLE(of, aspeed_sgpio_of_table);
> >  
> >  static int __init aspeed_sgpio_probe(struct platform_device *pdev)
> >  {
> > +	u32 nr_gpios, sgpio_freq, sgpio_clk_div, max_ngpios;
> >  	struct aspeed_sgpio *gpio;
> > -	u32 nr_gpios, sgpio_freq, sgpio_clk_div;
> >  	int rc;
> >  	unsigned long apb_freq;
> >  
> > @@ -489,13 +535,24 @@ static int __init aspeed_sgpio_probe(struct 
> > platform_device *pdev)
> >  	if (IS_ERR(gpio->base))
> >  		return PTR_ERR(gpio->base);
> >  
> > +	rc = of_property_read_u32(pdev->dev.of_node, "max-ngpios", 
> > &max_ngpios);
> > +	if (rc < 0) {
> > +		dev_err(&pdev->dev, "Could not read max-ngpios property\n");
> > +		return -EINVAL;
> 
> I don't think this is right. You should just fall back to using the 
> hard-coded value.
> 

I will use fallback value rather than returning error. 

> Cheers,
> 
> Andrew

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