Re: [PATCH v5 2/3] gpio: pcie-idio-24: Migrate to the regmap API

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Sun, Mar 26, 2023 at 12:25:58PM -0400, William Breathitt Gray wrote:
> The regmap API supports IO port accessors so we can take advantage of
> regmap abstractions rather than handling access to the device registers
> directly in the driver.
> 
> For the PCIe-IDIO-24 series of devices, the following BARs are
> available:
> 
>     BAR[0]: memory mapped PEX8311
>     BAR[1]: I/O mapped PEX8311
>     BAR[2]: I/O mapped card registers
> 
> There are 24 FET Output lines, 24 Isolated Input lines, and 8 TTL/CMOS
> lines (which may be configured for either output or input). The GPIO
> lines are exposed by the following card registers:
> 
>     Base +0x0-0x2 (Read/Write): FET Outputs
>     Base +0xB (Read/Write): TTL/CMOS
>     Base +0x4-0x6 (Read): Isolated Inputs
>     Base +0x7 (Read): TTL/CMOS
> 
> In order for the device to support interrupts, the PLX PEX8311 internal
> PCI wire interrupt and local interrupt input must first be enabled.
> 
> The following card registers for Change-Of-State may be used:
> 
>     Base +0x8-0xA (Read): COS Status Inputs
>     Base +0x8-0xA (Write): COS Clear Inputs
>     Base +0xB (Read): COS Status TTL/CMOS
>     Base +0xB (Write): COS Clear TTL/CMOS
>     Base +0xE (Read/Write): COS Enable
> 
> The COS Enable register is used to enable/disable interrupts and
> configure the interrupt levels; each bit maps to a group of eight inputs
> as described below:
> 
>     Bit 0: IRQ EN Rising Edge IN0-7
>     Bit 1: IRQ EN Rising Edge IN8-15
>     Bit 2: IRQ EN Rising Edge IN16-23
>     Bit 3: IRQ EN Rising Edge TTL0-7
>     Bit 4: IRQ EN Falling Edge IN0-7
>     Bit 5: IRQ EN Falling Edge IN8-15
>     Bit 6: IRQ EN Falling Edge IN16-23
>     Bit 7: IRQ EN Falling Edge TTL0-7
> 
> An interrupt is asserted when a change-of-state matching the interrupt
> level configuration respective for a particular group of eight inputs
> with enabled COS is detected.
> 
> The COS Status registers may be read to determine which inputs have
> changed; if interrupts were enabled, an IRQ will be generated for the
> set bits in these registers. Writing the value read from the COS Status
> register back to the respective COS Clear register will clear just those
> interrupts.

...

> Cc: Arnaud de Turckheim <quarium@gmail.com>
> Cc: John Hentges <jhentges@accesio.com>
> Cc: Jay Dolan <jay.dolan@accesio.com>

You can use --cc parameter to the `git format-patch`.

...

> +static const struct regmap_config pex8311_intcsr_regmap_config = {
> +	.name = "pex8311_intcsr",
> +	.reg_bits = 32,
> +	.reg_stride = 1,
> +	.reg_base = PLX_PEX8311_PCI_LCS_INTCSR,
> +	.val_bits = 32,
> +	.io_port = true,
> +	.max_register = 0x0,
> +};

Do you need regmap lock? If so, what for?

...

> +static const struct regmap_config idio_24_regmap_config = {
> +	.reg_bits = 8,
> +	.reg_stride = 1,
> +	.val_bits = 8,
> +	.io_port = true,
> +	.max_register = 0xF,
> +	.wr_table = &idio_24_wr_table,
> +	.rd_table = &idio_24_rd_table,
> +	.volatile_table = &idio_24_volatile_table,
> +	.cache_type = REGCACHE_FLAT,
> +};

Ditto.

...

> +static int idio_24_set_type_config(unsigned int **const buf, const unsigned int type,
> +				   const struct regmap_irq *const irq_data, const int idx,
> +				   void *const irq_drv_data)
>  {
> +	const unsigned int offset = irq_data->reg_offset;
> +	const unsigned int rising = COS_ENABLE_RISING << offset;
> +	const unsigned int falling = COS_ENABLE_FALLING << offset;
> +	const unsigned int mask = COS_ENABLE_BOTH << offset;
> +	struct idio_24_gpio *const idio24gpio = irq_drv_data;
> +	unsigned int new;
> +	unsigned int cos_enable;
> +	int ret;
> +
> +	switch (type) {
> +	case IRQ_TYPE_EDGE_RISING:
> +		new = rising;
> +		break;
> +	case IRQ_TYPE_EDGE_FALLING:
> +		new = falling;
> +		break;
> +	case IRQ_TYPE_EDGE_BOTH:
> +		new = mask;
> +		break;
> +	default:
> +		return -EINVAL;
>  	}
>  
> +	raw_spin_lock(&idio24gpio->lock);
>  
> +	/* replace old bitmap with new bitmap */
> +	idio24gpio->irq_type = (idio24gpio->irq_type & ~mask) | (new & mask);
>  
> +	ret = regmap_read(idio24gpio->map, IDIO_24_COS_ENABLE, &cos_enable);
> +	if (ret)
> +		goto exit_early;
>  
> +	/* if COS is currently enabled then update the edge type */
> +	if (cos_enable & mask) {
> +		ret = regmap_update_bits(idio24gpio->map, IDIO_24_COS_ENABLE, mask,
> +					 idio24gpio->irq_type);
> +		goto exit_early;
>  	}

> +exit_early:

More descriptive is to call it

exit_unlock:

The rule of thumb is to explain what _will_ happen, if we goto $LABEL.

> +	raw_spin_unlock(&idio24gpio->lock);
>  
> +	return ret;
>  }

-- 
With Best Regards,
Andy Shevchenko