Re: [RESEND PATCH] iio: addac: stx104: Add 8254 Counter/Timer support

From: Jonathan Cameron
Date: Sun Sep 17 2023 - 05:32:15 EST

On Sat, 16 Sep 2023 07:20:31 -0400
William Breathitt Gray <william.gray@xxxxxxxxxx> 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@xxxxxxxxxx>
> ---
> 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@xxxxxxxxx>");
> MODULE_DESCRIPTION("Apex Embedded Systems STX104 IIO driver");
> MODULE_LICENSE("GPL v2");
> +MODULE_IMPORT_NS(I8254);
>
> base-commit: 9dc03309fe9ba9f9b26a37b2dd4fa2d5111a1ccf