iio: adc: stm32-dfsdm: Add support for stm32mp1

Add support for DFSDM (Digital Filter For Sigma Delta Modulators)
to STM32MP1. This variant is close to STM32H7 DFSDM, it implements
6 filter instances. Registers map is also increased.
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.txt

@@ -8,14 +8,16 @@ It is mainly targeted for:
 - PDM microphones (audio digital microphone)
 
 It features up to 8 serial digital interfaces (SPI or Manchester) and
-up to 4 filters on stm32h7.
+up to 4 filters on stm32h7 or 6 filters on stm32mp1.
 
 Each child node match with a filter instance.
 
 Contents of a STM32 DFSDM root node:
 ------------------------------------
 Required properties:
-- compatible: Should be "st,stm32h7-dfsdm".
+- compatible: Should be one of:
+  "st,stm32h7-dfsdm"
+  "st,stm32mp1-dfsdm"
 - reg: Offset and length of the DFSDM block register set.
 - clocks: IP and serial interfaces clocking. Should be set according
 		to rcc clock ID and "clock-names".
@@ -45,6 +47,7 @@ Required properties:
 	"st,stm32-dfsdm-adc" for sigma delta ADCs
 	"st,stm32-dfsdm-dmic" for audio digital microphone.
 - reg: Specifies the DFSDM filter instance used.
+	Valid values are from 0 to 3 on stm32h7, 0 to 5 on stm32mp1.
 - interrupts: IRQ lines connected to each DFSDM filter instance.
 - st,adc-channels:	List of single-ended channels muxed for this ADC.
 			valid values:

drivers/iio/adc/stm32-dfsdm-core.c

@@ -25,6 +25,8 @@ struct stm32_dfsdm_dev_data {
 
 #define STM32H7_DFSDM_NUM_FILTERS	4
 #define STM32H7_DFSDM_NUM_CHANNELS	8
+#define STM32MP1_DFSDM_NUM_FILTERS	6
+#define STM32MP1_DFSDM_NUM_CHANNELS	8
 
 static bool stm32_dfsdm_volatile_reg(struct device *dev, unsigned int reg)
 {
@@ -61,6 +63,21 @@ static const struct stm32_dfsdm_dev_data stm32h7_dfsdm_data = {
 	.regmap_cfg = &stm32h7_dfsdm_regmap_cfg,
 };
 
+static const struct regmap_config stm32mp1_dfsdm_regmap_cfg = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = sizeof(u32),
+	.max_register = 0x7fc,
+	.volatile_reg = stm32_dfsdm_volatile_reg,
+	.fast_io = true,
+};
+
+static const struct stm32_dfsdm_dev_data stm32mp1_dfsdm_data = {
+	.num_filters = STM32MP1_DFSDM_NUM_FILTERS,
+	.num_channels = STM32MP1_DFSDM_NUM_CHANNELS,
+	.regmap_cfg = &stm32mp1_dfsdm_regmap_cfg,
+};
+
 struct dfsdm_priv {
 	struct platform_device *pdev; /* platform device */
 
@@ -248,6 +265,10 @@ static const struct of_device_id stm32_dfsdm_of_match[] = {
 		.compatible = "st,stm32h7-dfsdm",
 		.data = &stm32h7_dfsdm_data,
 	},
+	{
+		.compatible = "st,stm32mp1-dfsdm",
+		.data = &stm32mp1_dfsdm_data,
+	},
 	{}
 };
 MODULE_DEVICE_TABLE(of, stm32_dfsdm_of_match);