iio: adc: stm32-dfsdm: add id registers support

Add support of identification registers to STM32 DFSDM
to allow hardware capabilities discovery and configuration check.
The number of filters and channels, are read from registers,
when they are available.

Signed-off-by: Olivier Moysan <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

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

···
  * Author(s): Arnaud Pouliquen <[e-mail]> for STMicroelectronics.
  */
 
+#include <linux/bitfield.h>
 #include <linux/clk.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
···
 
 #include "stm32-dfsdm.h"
 
+/**
+ * struct stm32_dfsdm_dev_data - DFSDM compatible configuration data
+ * @ipid: DFSDM identification number. Used only if hardware provides identification registers
+ * @num_filters: DFSDM number of filters. Unused if identification registers are available
+ * @num_channels: DFSDM number of channels. Unused if identification registers are available
+ * @regmap_cfg: SAI register map configuration pointer
+ */
 struct stm32_dfsdm_dev_data {
+	u32 ipid;
 	unsigned int num_filters;
 	unsigned int num_channels;
 	const struct regmap_config *regmap_cfg;
···
 
 #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)
 {
···
 };
 
 static const struct stm32_dfsdm_dev_data stm32mp1_dfsdm_data = {
-	.num_filters = STM32MP1_DFSDM_NUM_FILTERS,
-	.num_channels = STM32MP1_DFSDM_NUM_CHANNELS,
+	.ipid = STM32MP15_IPIDR_NUMBER,
 	.regmap_cfg = &stm32mp1_dfsdm_regmap_cfg,
 };
 
···
 };
 MODULE_DEVICE_TABLE(of, stm32_dfsdm_of_match);
 
+static int stm32_dfsdm_probe_identification(struct platform_device *pdev,
+					    struct dfsdm_priv *priv,
+					    const struct stm32_dfsdm_dev_data *dev_data)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct device_node *child;
+	struct stm32_dfsdm *dfsdm = &priv->dfsdm;
+	const char *compat;
+	int ret, count = 0;
+	u32 id, val;
+
+	if (!dev_data->ipid) {
+		dfsdm->num_fls = dev_data->num_filters;
+		dfsdm->num_chs = dev_data->num_channels;
+		return 0;
+	}
+
+	ret = regmap_read(dfsdm->regmap, DFSDM_IPIDR, &id);
+	if (ret)
+		return ret;
+
+	if (id != dev_data->ipid) {
+		dev_err(&pdev->dev, "Unexpected IP version: 0x%x", id);
+		return -EINVAL;
+	}
+
+	for_each_child_of_node(np, child) {
+		ret = of_property_read_string(child, "compatible", &compat);
+		if (ret)
+			continue;
+		/* Count only child nodes with dfsdm compatible */
+		if (strstr(compat, "dfsdm"))
+			count++;
+	}
+
+	ret = regmap_read(dfsdm->regmap, DFSDM_HWCFGR, &val);
+	if (ret)
+		return ret;
+
+	dfsdm->num_fls = FIELD_GET(DFSDM_HWCFGR_NBF_MASK, val);
+	dfsdm->num_chs = FIELD_GET(DFSDM_HWCFGR_NBT_MASK, val);
+
+	if (count > dfsdm->num_fls) {
+		dev_err(&pdev->dev, "Unexpected child number: %d", count);
+		return -EINVAL;
+	}
+
+	ret = regmap_read(dfsdm->regmap, DFSDM_VERR, &val);
+	if (ret)
+		return ret;
+
+	dev_dbg(&pdev->dev, "DFSDM version: %lu.%lu. %d channels/%d filters\n",
+		FIELD_GET(DFSDM_VERR_MAJREV_MASK, val),
+		FIELD_GET(DFSDM_VERR_MINREV_MASK, val),
+		dfsdm->num_chs, dfsdm->num_fls);
+
+	return 0;
+}
+
 static int stm32_dfsdm_probe(struct platform_device *pdev)
 {
 	struct dfsdm_priv *priv;
···
 	dev_data = of_device_get_match_data(&pdev->dev);
 
 	dfsdm = &priv->dfsdm;
-	dfsdm->fl_list = devm_kcalloc(&pdev->dev, dev_data->num_filters,
-				      sizeof(*dfsdm->fl_list), GFP_KERNEL);
-	if (!dfsdm->fl_list)
-		return -ENOMEM;
-
-	dfsdm->num_fls = dev_data->num_filters;
-	dfsdm->ch_list = devm_kcalloc(&pdev->dev, dev_data->num_channels,
-				      sizeof(*dfsdm->ch_list),
-				      GFP_KERNEL);
-	if (!dfsdm->ch_list)
-		return -ENOMEM;
-	dfsdm->num_chs = dev_data->num_channels;
 
 	ret = stm32_dfsdm_parse_of(pdev, priv);
 	if (ret < 0)
···
 			__func__, ret);
 		return ret;
 	}
+
+	ret = stm32_dfsdm_probe_identification(pdev, priv, dev_data);
+	if (ret < 0)
+		return ret;
+
+	dfsdm->fl_list = devm_kcalloc(&pdev->dev, dfsdm->num_fls,
+				      sizeof(*dfsdm->fl_list), GFP_KERNEL);
+	if (!dfsdm->fl_list)
+		return -ENOMEM;
+
+	dfsdm->ch_list = devm_kcalloc(&pdev->dev, dfsdm->num_chs,
+				      sizeof(*dfsdm->ch_list), GFP_KERNEL);
+	if (!dfsdm->ch_list)
+		return -ENOMEM;
 
 	platform_set_drvdata(pdev, dfsdm);
 

drivers/iio/adc/stm32-dfsdm.h

···
 
 /*
  * STM32 DFSDM - global register map
- * ________________________________________________________
- * | Offset |                 Registers block             |
- * --------------------------------------------------------
- * | 0x000  |      CHANNEL 0 + COMMON CHANNEL FIELDS      |
- * --------------------------------------------------------
- * | 0x020  |                CHANNEL 1                    |
- * --------------------------------------------------------
- * | ...    |                .....                        |
- * --------------------------------------------------------
- * | 0x0E0  |                CHANNEL 7                    |
- * --------------------------------------------------------
- * | 0x100  |      FILTER  0 + COMMON  FILTER FIELDs      |
- * --------------------------------------------------------
- * | 0x200  |                FILTER  1                    |
- * --------------------------------------------------------
- * | 0x300  |                FILTER  2                    |
- * --------------------------------------------------------
- * | 0x400  |                FILTER  3                    |
- * --------------------------------------------------------
+ * __________________________________________________________
+ * | Offset    |             Registers block                |
+ * ----------------------------------------------------------
+ * | 0x000     |      CHANNEL 0 + COMMON CHANNEL FIELDS     |
+ * ----------------------------------------------------------
+ * | 0x020     |                CHANNEL 1                   |
+ * ----------------------------------------------------------
+ * | ...       |                 .....                      |
+ * ----------------------------------------------------------
+ * | 0x20 x n  |                CHANNEL n                   |
+ * ----------------------------------------------------------
+ * | 0x100     |      FILTER  0 + COMMON FILTER FIELDs      |
+ * ----------------------------------------------------------
+ * | 0x200     |                FILTER  1                   |
+ * ----------------------------------------------------------
+ * |           |                 .....                      |
+ * ----------------------------------------------------------
+ * | 0x100 x m |                FILTER  m                   |
+ * ----------------------------------------------------------
+ * |           |                 .....                      |
+ * ----------------------------------------------------------
+ * | 0x7F0-7FC |         Identification registers           |
+ * ----------------------------------------------------------
  */
 
 /*
···
 #define DFSDM_AWCFR_AWLTF(v)	FIELD_PREP(DFSDM_AWCFR_AWLTF_MASK, v)
 #define DFSDM_AWCFR_AWHTF_MASK	GENMASK(15, 8)
 #define DFSDM_AWCFR_AWHTF(v)	FIELD_PREP(DFSDM_AWCFR_AWHTF_MASK, v)
+
+/*
+ * Identification register definitions
+ */
+#define DFSDM_HWCFGR		0x7F0
+#define DFSDM_VERR		0x7F4
+#define DFSDM_IPIDR		0x7F8
+#define DFSDM_SIDR		0x7FC
+
+/* HWCFGR: Hardware configuration register */
+#define DFSDM_HWCFGR_NBT_MASK	GENMASK(7, 0)
+#define DFSDM_HWCFGR_NBF_MASK	GENMASK(15, 8)
+
+/* VERR: Version register */
+#define DFSDM_VERR_MINREV_MASK	GENMASK(3, 0)
+#define DFSDM_VERR_MAJREV_MASK	GENMASK(7, 4)
+
+#define STM32MP15_IPIDR_NUMBER	0x00110031
 
 /* DFSDM filter order  */
 enum stm32_dfsdm_sinc_order {