Re: [PATCH v4 2/8] pinctrl: sh-pfc: r8a7790: Implement voltage switching for SDHI

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Ben Hutchings <ben.hutchings@codethink.co.uk>
Cc: Ian Molton <ian@mnementh.co.uk>,
	linux-mmc@vger.kernel.org, linux-sh@vger.kernel.org,
	linux-gpio@vger.kernel.org, linux-kernel@lists.codethink.co.uk,
	Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>,
	Simon Horman <horms@verge.net.au>,
	Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Subject: Re: [PATCH v4 2/8] pinctrl: sh-pfc: r8a7790: Implement voltage switching for SDHI
Date: Wed, 01 Jul 2015 07:37:20 +0000	[thread overview]
Message-ID: <6355006.FnTDFbP0bb@avalon> (raw)
In-Reply-To: <1435683249.23818.62.camel@codethink.co.uk>

Hi Ben,

Thank you for the patch.

On Tuesday 30 June 2015 17:54:09 Ben Hutchings wrote:
> All the SHDIs can operate with either 3.3V or 1.8V signals, depending
> on negotiation with the card.
> 
> Implement the {get,set}_io_voltage operations and set the related
> capability flag for the associated pins.
> 
> Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
> ---
>  drivers/pinctrl/sh-pfc/core.c        |  2 +-
>  drivers/pinctrl/sh-pfc/core.h        |  1 +
>  drivers/pinctrl/sh-pfc/pfc-r8a7790.c | 71 ++++++++++++++++++++++++++++++++-
>  3 files changed, 72 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pinctrl/sh-pfc/core.c b/drivers/pinctrl/sh-pfc/core.c
> index 7b2c9495c383..7d51f96afc9a 100644
> --- a/drivers/pinctrl/sh-pfc/core.c
> +++ b/drivers/pinctrl/sh-pfc/core.c
> @@ -92,7 +92,7 @@ static int sh_pfc_map_resources(struct sh_pfc *pfc,
>  	return 0;
>  }
> 
> -static void __iomem *sh_pfc_phys_to_virt(struct sh_pfc *pfc, u32 reg)
> +void __iomem *sh_pfc_phys_to_virt(struct sh_pfc *pfc, u32 reg)
>  {
>  	struct sh_pfc_window *window;
>  	phys_addr_t address = reg;
> diff --git a/drivers/pinctrl/sh-pfc/core.h b/drivers/pinctrl/sh-pfc/core.h
> index 6dc8a6fc2746..af355629c5d2 100644
> --- a/drivers/pinctrl/sh-pfc/core.h
> +++ b/drivers/pinctrl/sh-pfc/core.h
> @@ -57,6 +57,7 @@ int sh_pfc_unregister_gpiochip(struct sh_pfc *pfc);
>  int sh_pfc_register_pinctrl(struct sh_pfc *pfc);
>  int sh_pfc_unregister_pinctrl(struct sh_pfc *pfc);
> 
> +void __iomem *sh_pfc_phys_to_virt(struct sh_pfc *pfc, u32 address);
>  u32 sh_pfc_read_raw_reg(void __iomem *mapped_reg, unsigned int reg_width);
>  void sh_pfc_write_raw_reg(void __iomem *mapped_reg, unsigned int reg_width,
> u32 data);
> diff --git a/drivers/pinctrl/sh-pfc/pfc-r8a7790.c
> b/drivers/pinctrl/sh-pfc/pfc-r8a7790.c index 22a5470889f5..ec6657de6a46
> 100644
> --- a/drivers/pinctrl/sh-pfc/pfc-r8a7790.c
> +++ b/drivers/pinctrl/sh-pfc/pfc-r8a7790.c
> @@ -21,6 +21,7 @@
>   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 
> USA */
> 
> +#include <linux/io.h>
>  #include <linux/kernel.h>
>  #include <linux/platform_data/gpio-rcar.h>
> 
> @@ -1739,10 +1740,20 @@ static const u16 pinmux_data[] = {
>  #define PIN_NUMBER(r, c) (((r) - 'A') * 31 + (c) + 200)
>  #define PIN_A_NUMBER(r, c) PIN_NUMBER(ROW_GROUP_A(r), c)
> 
> +#define PIN_IO_VOLTAGE(bank, _pin, _name, sfx)		\
> +	[RCAR_GP_PIN(bank, _pin)].configs = SH_PFC_PIN_CFG_IO_VOLTAGE
> +
>  static const struct sh_pfc_pin pinmux_pins[] = {
>  	PINMUX_GPIO_GP_ALL(),
> 
> -	/* Pins not associated with a GPIO port */
> +	/*
> +	 * All pins assigned to GPIO bank 3 can be used for SD interfaces
> +	 * in which case they support both 3.3V and 1.8V signalling.
> +	 */
> +	PORT_GP_32(3, PIN_IO_VOLTAGE, unused),
> +
> +	/* Pins not associated with a GPIO port, placed after all the GPIOs */
> +	[RCAR_GP_PIN(5, 31) + 1] 
I'm sorry but I still don't like this. gcc outputs a warning when overriding 
an initializer if you enable -Wextra, which leads me to believe this construct 
is dubious. It should at least be tested with LLVM.

I'd much prefer replacing PINMUX_GPIO_GP_ALL() with a version that will 
initialize the pins correctly right away.

Another option which might be better would be to add a new operation to 
retrieve the pin config bitmask instead of storing it in sh_pfc_pin. Most SoCs 
don't have per-pin config bitmasks, so we could save a bit of memory by doing 
so. r8a73a4 and r8a7790 could easily compute the bitmask in C code, while 
sh73a0 and r8a7740 would have a private table. The drawback would be a 
slightly increased execution time.

>  	SH_PFC_PIN_NAMED(ROW_GROUP_A('F'), 15, AF15),
>  	SH_PFC_PIN_NAMED(ROW_GROUP_A('G'), 15, AG15),
>  	SH_PFC_PIN_NAMED(ROW_GROUP_A('H'), 15, AH15),
> @@ -4595,6 +4606,58 @@ static const char * const vin3_groups[] = {
>  	"vin3_clk",
>  };
> 
> +static int sdhi_get_io_voltage(struct sh_pfc *pfc, unsigned int pin)
> +{
> +	void __iomem *mapped_reg;
> +	u32 data, mask;
> +
> +	if (WARN(pin < RCAR_GP_PIN(3, 0) || pin > RCAR_GP_PIN(3, 31),
> +		 "sdhi_get_low_voltage: invalid pin %#x", pin))

The function name is wrong. You could use __func__, but as WARN() will output 
a backtrace I think you can just drop it. And given that this shouldn't happen 
at all given that only port 3 pins have the IO_VOLTAGE flag set, I'd just drop 
the warning completely. Same for shdi_set_io_voltage().

> +		return -EIO;
> +
> +	/* Map IOCTRL6 */
> +	mapped_reg = sh_pfc_phys_to_virt(pfc, 0xe606008c);
> +
> +	/* Bits in IOCTRL6 are numbered in opposite order to pins */
> +	mask = 0x80000000 >> (pin & 0x1f);
> +
> +	data = ioread32(mapped_reg);
> +
> +	return (data & mask) ? 3300 : 1800;
> +}
> +
> +static int
> +sdhi_set_io_voltage(struct sh_pfc *pfc, unsigned int pin, u16 voltage_mV)
> +{
> +	void __iomem *mapped_reg;
> +	u32 data, mask;
> +
> +	if (WARN(pin < RCAR_GP_PIN(3, 0) || pin > RCAR_GP_PIN(3, 31),
> +		 "invalid pin %#x", pin))
> +		return -EIO;
> +
> +	if (voltage_mV != 1800 && voltage_mV != 3300)
> +		return -EINVAL;
> +
> +	/* Map IOCTRL6 */
> +	mapped_reg = sh_pfc_phys_to_virt(pfc, 0xe606008c);
> +
> +	/* Bits in IOCTRL6 are numbered in opposite order to pins */
> +	mask = 0x80000000 >> (pin & 0x1f);
> +
> +	data = ioread32(mapped_reg);
> +
> +	if (voltage_mV = 3300)
> +		data |= mask;
> +	else
> +		data &= ~mask;
> +
> +	iowrite32(~data, sh_pfc_phys_to_virt(pfc, pfc->info->unlock_reg));
> +	iowrite32(data, mapped_reg);
> +
> +	return 0;
> +}
> +
>  static const struct sh_pfc_function pinmux_functions[] = {
>  	SH_PFC_FUNCTION(audio_clk),
>  	SH_PFC_FUNCTION(avb),
> @@ -5586,8 +5649,14 @@ static const struct pinmux_cfg_reg
> pinmux_config_regs[] = { { },
>  };
> 
> +static const struct sh_pfc_soc_operations pinmux_ops = {
> +	.get_io_voltage = sdhi_get_io_voltage,
> +	.set_io_voltage = sdhi_set_io_voltage,
> +};
> +
>  const struct sh_pfc_soc_info r8a7790_pinmux_info = {
>  	.name = "r8a77900_pfc",
> +	.ops = &pinmux_ops,
>  	.unlock_reg = 0xe6060000, /* PMMR */
> 
>  	.function = { PINMUX_FUNCTION_BEGIN, PINMUX_FUNCTION_END },

-- 
Regards,

Laurent Pinchart