linux-kernel - Re: [PATCH v2 3/5] input: himax_hx83112b: implement MCU register reading

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Message-ID: <ZkKb5_SRNwG1pRou@google.com>
Date: Mon, 13 May 2024 16:01:59 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Felix Kaechele <felix@...chele.ca>, Mark Brown <broonie@...nel.org>
Cc: Job Noorman <job@...rman.info>, Rob Herring <robh+dt@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>, linux-input@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/5] input: himax_hx83112b: implement MCU register
 reading

On Sat, May 11, 2024 at 08:12:24AM -0400, Felix Kaechele wrote:
> Implement reading from the MCU in a more universal fashion. This allows
> properly handling reads of more than 4 bytes using the AHB FIFO
> implemented in the chip.

Mark, do we have anything in regmap to support this better or having a
wrapper is the best solution here?

Thanks!

> 
> Signed-off-by: Felix Kaechele <felix@...chele.ca>
> ---
>  drivers/input/touchscreen/himax_hx83112b.c | 50 ++++++++++++++++++++--
>  1 file changed, 47 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/himax_hx83112b.c b/drivers/input/touchscreen/himax_hx83112b.c
> index 2da2920d43f9..67ef3255cc8b 100644
> --- a/drivers/input/touchscreen/himax_hx83112b.c
> +++ b/drivers/input/touchscreen/himax_hx83112b.c
> @@ -27,9 +27,13 @@
>  #define HIMAX_AHB_ADDR_BYTE_0			0x00
>  #define HIMAX_AHB_ADDR_RDATA_BYTE_0		0x08
>  #define HIMAX_AHB_ADDR_ACCESS_DIRECTION		0x0c
> +#define HIMAX_AHB_ADDR_INCR4			0x0d
> +#define HIMAX_AHB_ADDR_CONTI			0x13
>  #define HIMAX_AHB_ADDR_EVENT_STACK		0x30
>  
>  #define HIMAX_AHB_CMD_ACCESS_DIRECTION_READ	0x00
> +#define HIMAX_AHB_CMD_INCR4			0x10
> +#define HIMAX_AHB_CMD_CONTI			0x31
>  
>  #define HIMAX_REG_ADDR_ICID			0x900000d0
>  
> @@ -65,10 +69,34 @@ static const struct regmap_config himax_regmap_config = {
>  	.val_format_endian = REGMAP_ENDIAN_LITTLE,
>  };
>  
> -static int himax_read_config(struct himax_ts_data *ts, u32 address, u32 *dst)
> +static int himax_bus_enable_burst(struct himax_ts_data *ts)
>  {
>  	int error;
>  
> +	error = regmap_write(ts->regmap, HIMAX_AHB_ADDR_CONTI,
> +			     HIMAX_AHB_CMD_CONTI);
> +	if (error)
> +		return error;
> +
> +	error = regmap_write(ts->regmap, HIMAX_AHB_ADDR_INCR4,
> +			     HIMAX_AHB_CMD_INCR4);
> +	if (error)
> +		return error;
> +
> +	return 0;
> +}
> +
> +static int himax_bus_read(struct himax_ts_data *ts, u32 address, void *dst,
> +			  size_t length)
> +{
> +	int error;
> +
> +	if (length > 4) {
> +		error = himax_bus_enable_burst(ts);
> +		if (error)
> +			return error;
> +	}
> +
>  	error = regmap_write(ts->regmap, HIMAX_AHB_ADDR_BYTE_0, address);
>  	if (error)
>  		return error;
> @@ -78,7 +106,23 @@ static int himax_read_config(struct himax_ts_data *ts, u32 address, u32 *dst)
>  	if (error)
>  		return error;
>  
> -	error = regmap_read(ts->regmap, HIMAX_AHB_ADDR_RDATA_BYTE_0, dst);
> +	if (length > 4)
> +		error = regmap_noinc_read(ts->regmap, HIMAX_AHB_ADDR_RDATA_BYTE_0,
> +					  dst, length);
> +	else
> +		error = regmap_read(ts->regmap, HIMAX_AHB_ADDR_RDATA_BYTE_0,
> +				    dst);
> +	if (error)
> +		return error;
> +
> +	return 0;
> +}
> +
> +static int himax_read_mcu(struct himax_ts_data *ts, u32 address, u32 *dst)
> +{
> +	int error;
> +
> +	error = himax_bus_read(ts, address, dst, sizeof(dst));
>  	if (error)
>  		return error;
>  
> @@ -104,7 +148,7 @@ static int himax_read_product_id(struct himax_ts_data *ts, u32 *product_id)
>  {
>  	int error;
>  
> -	error = himax_read_config(ts, HIMAX_REG_ADDR_ICID, product_id);
> +	error = himax_read_mcu(ts, HIMAX_REG_ADDR_ICID, product_id);
>  	if (error)
>  		return error;
>  
> -- 
> 2.45.0
> 

-- 
Dmitry