iio: addac: stx104: Add 8254 Counter/Timer support

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>
Link: https://lore.kernel.org/r/20230916112031.3634-1-william.gray@linaro.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/addac/Kconfig b/drivers/iio/addac/Kconfig
index 877f9124803c9c437749e31879cafba374e7b4bc..b2623881f0ec4e4b6fb440f949fcebca8fd5c697 100644 (file)
--- 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 d1f7ce033b46e59000b3405931ccdeba41234741..6946a65512ca29ca0f89ef499873c6a50ee82202 100644 (file)
--- 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);