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Date:   Sun, 17 Sep 2023 10:30:59 +0100
From:   Jonathan Cameron <jic23@kernel.org>
To:     William Breathitt Gray <william.gray@linaro.org>
Cc:     Lars-Peter Clausen <lars@metafoo.de>, linux-iio@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RESEND PATCH] iio: addac: stx104: Add 8254 Counter/Timer
 support
Message-ID: <20230917103059.41730dbd@jic23-huawei>
In-Reply-To: <20230916112031.3634-1-william.gray@linaro.org>
References: <20230916112031.3634-1-william.gray@linaro.org>
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On Sat, 16 Sep 2023 07:20:31 -0400
William Breathitt Gray <william.gray@linaro.org> wrote:

> The STX104 features an 8254 Counter/Timer chip providing three
> counter/timers which can be used for frequency measurement, frequency
> output, pulse width modulation, pulse width measurement, event count,
> etc. The STX104 provides a register bank selection to bank select
> between the 8254 Bank and the Indexed Register Array Bank; the Indexed
> Register Array is not utilized by this driver, so the 8254 Bank is
> selected unconditionally.
> 
> Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
> ---
> Looks like this was missed in the last merge cycle, so I'm resending it
> now as requested. [^1]
> 
> [^1]: https://lore.kernel.org/all/ZJoO++gEMiDsZioz@fedora/
Ah. I indeed missed this entirely - saw counters in the patch title and failed
to notice it was being added to an IIO driver :(  Sorry about that.

Anyhow, LGTM. Applied to the togreg branch of iio.git and pushed out as testing
for 0-day etc to poke at it and see if we missed anything.

Thanks,

Jonathan

> 
>  drivers/iio/addac/Kconfig  |  1 +
>  drivers/iio/addac/stx104.c | 61 ++++++++++++++++++++++++++++++++++++--
>  2 files changed, 60 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/addac/Kconfig b/drivers/iio/addac/Kconfig
> index 877f9124803c..b2623881f0ec 100644
> --- a/drivers/iio/addac/Kconfig
> +++ b/drivers/iio/addac/Kconfig
> @@ -38,6 +38,7 @@ config STX104
>  	select REGMAP_MMIO
>  	select GPIOLIB
>  	select GPIO_REGMAP
> +	select I8254
>  	help
>  	  Say yes here to build support for the Apex Embedded Systems STX104
>  	  integrated analog PC/104 card.
> diff --git a/drivers/iio/addac/stx104.c b/drivers/iio/addac/stx104.c
> index d1f7ce033b46..6946a65512ca 100644
> --- a/drivers/iio/addac/stx104.c
> +++ b/drivers/iio/addac/stx104.c
> @@ -8,6 +8,7 @@
>  #include <linux/device.h>
>  #include <linux/err.h>
>  #include <linux/gpio/regmap.h>
> +#include <linux/i8254.h>
>  #include <linux/iio/iio.h>
>  #include <linux/iio/types.h>
>  #include <linux/isa.h>
> @@ -55,6 +56,7 @@ MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
>  #define STX104_ADC_STATUS (STX104_AIO_BASE + 0x8)
>  #define STX104_ADC_CONTROL (STX104_AIO_BASE + 0x9)
>  #define STX104_ADC_CONFIGURATION (STX104_AIO_BASE + 0x11)
> +#define STX104_I8254_BASE (STX104_AIO_BASE + 0x12)
>  
>  #define STX104_AIO_DATA_STRIDE 2
>  #define STX104_DAC_OFFSET(_channel) (STX104_DAC_BASE + STX104_AIO_DATA_STRIDE * (_channel))
> @@ -77,6 +79,7 @@ MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
>  /* ADC Configuration */
>  #define STX104_GAIN GENMASK(1, 0)
>  #define STX104_ADBU BIT(2)
> +#define STX104_RBK GENMASK(7, 4)
>  #define STX104_BIPOLAR 0
>  #define STX104_GAIN_X1 0
>  #define STX104_GAIN_X2 1
> @@ -168,6 +171,32 @@ static const struct regmap_config dio_regmap_config = {
>  	.io_port = true,
>  };
>  
> +static const struct regmap_range pit_wr_ranges[] = {
> +	regmap_reg_range(0x0, 0x3),
> +};
> +static const struct regmap_range pit_rd_ranges[] = {
> +	regmap_reg_range(0x0, 0x2),
> +};
> +static const struct regmap_access_table pit_wr_table = {
> +	.yes_ranges = pit_wr_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(pit_wr_ranges),
> +};
> +static const struct regmap_access_table pit_rd_table = {
> +	.yes_ranges = pit_rd_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(pit_rd_ranges),
> +};
> +
> +static const struct regmap_config pit_regmap_config = {
> +	.name = "i8254",
> +	.reg_bits = 8,
> +	.reg_stride = 1,
> +	.reg_base = STX104_I8254_BASE,
> +	.val_bits = 8,
> +	.io_port = true,
> +	.wr_table = &pit_wr_table,
> +	.rd_table = &pit_rd_table,
> +};
> +
>  static int stx104_read_raw(struct iio_dev *indio_dev,
>  	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
>  {
> @@ -339,6 +368,21 @@ static const char *stx104_names[STX104_NGPIO] = {
>  	"DIN0", "DIN1", "DIN2", "DIN3", "DOUT0", "DOUT1", "DOUT2", "DOUT3"
>  };
>  
> +static int bank_select_i8254(struct regmap *map)
> +{
> +	const u8 select_i8254[] = { 0x3, 0xB, 0xA };
> +	size_t i;
> +	int err;
> +
> +	for (i = 0; i < ARRAY_SIZE(select_i8254); i++) {
> +		err = regmap_write_bits(map, STX104_ADC_CONFIGURATION, STX104_RBK, select_i8254[i]);
> +		if (err)
> +			return err;
> +	}
> +
> +	return 0;
> +}
> +
>  static int stx104_init_hw(struct stx104_iio *const priv)
>  {
>  	int err;
> @@ -361,7 +405,7 @@ static int stx104_init_hw(struct stx104_iio *const priv)
>  	if (err)
>  		return err;
>  
> -	return 0;
> +	return bank_select_i8254(priv->aio_ctl_map);
>  }
>  
>  static int stx104_probe(struct device *dev, unsigned int id)
> @@ -369,6 +413,7 @@ static int stx104_probe(struct device *dev, unsigned int id)
>  	struct iio_dev *indio_dev;
>  	struct stx104_iio *priv;
>  	struct gpio_regmap_config gpio_config;
> +	struct i8254_regmap_config pit_config;
>  	void __iomem *stx104_base;
>  	struct regmap *aio_ctl_map;
>  	struct regmap *aio_data_map;
> @@ -406,6 +451,11 @@ static int stx104_probe(struct device *dev, unsigned int id)
>  		return dev_err_probe(dev, PTR_ERR(dio_map),
>  				     "Unable to initialize dio register map\n");
>  
> +	pit_config.map = devm_regmap_init_mmio(dev, stx104_base, &pit_regmap_config);
> +	if (IS_ERR(pit_config.map))
> +		return dev_err_probe(dev, PTR_ERR(pit_config.map),
> +				     "Unable to initialize i8254 register map\n");
> +
>  	priv = iio_priv(indio_dev);
>  	priv->aio_ctl_map = aio_ctl_map;
>  	priv->aio_data_map = aio_data_map;
> @@ -449,7 +499,13 @@ static int stx104_probe(struct device *dev, unsigned int id)
>  		.drvdata = dio_map,
>  	};
>  
> -	return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &gpio_config));
> +	err = PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &gpio_config));
> +	if (err)
> +		return err;
> +
> +	pit_config.parent = dev;
> +
> +	return devm_i8254_regmap_register(dev, &pit_config);
>  }
>  
>  static struct isa_driver stx104_driver = {
> @@ -464,3 +520,4 @@ module_isa_driver(stx104_driver, num_stx104);
>  MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
>  MODULE_DESCRIPTION("Apex Embedded Systems STX104 IIO driver");
>  MODULE_LICENSE("GPL v2");
> +MODULE_IMPORT_NS(I8254);
> 
> base-commit: 9dc03309fe9ba9f9b26a37b2dd4fa2d5111a1ccf