board: toradex: apalis/colibri imx6: Detect new v1.2 SoM variant

Apalis/Colibri iMX6 V1.2 will replace the STMPE811 ADC/Touch controller
which is EOL by the TLA2024 ADC and AD7879 touch controller.

To support this new version, we detect the presence of the TLA2024
during boot and set a new environment variable named "variant". This
will allow us and users to select the correct DT easily.

By probing via I2C we have a robust detection method instead of relying
on the existing "board_rev" environment variable which is set by the
config block. Users can use "variant" in their DT selection and do not
have to map the board revision to a device tree.

"variant" environment variable behaviour:
* Empty or absent for all versions below v1.2 (STMPE811)
* "-v1.2" for all versions starting from v1.2 (TLA2024 + AD7879)

Usage example:
setenv fdtfile imx6q-apalis${variant}-${fdt_board}.dtb

Signed-off-by: Ernest Van Hoecke <ernest.vanhoecke@toradex.com>
Reviewed-by: Francesco Dolcini <francesco.dolcini@toradex.com>

board/toradex/apalis_imx6/apalis_imx6.c

@@ -36,6 +36,7 @@
 #include <dwc_ahsata.h>
 #include <env.h>
 #include <fsl_esdhc_imx.h>
+#include <i2c.h>
 #include <imx_thermal.h>
 #include <micrel.h>
 #include <miiphy.h>
@@ -77,6 +78,8 @@ DECLARE_GLOBAL_DATA_PTR;
 
 #define APALIS_IMX6_SATA_INIT_RETRIES	10
 
+#define I2C_PWR	1
+
 int dram_init(void)
 {
 	/* use the DDR controllers configured size */
@@ -689,6 +692,32 @@ int board_init(void)
 	return 0;
 }
 
+static bool is_som_variant_1_2(void)
+{
+	struct udevice *bus;
+	struct udevice *i2c_dev;
+	int ret;
+
+	ret = uclass_get_device_by_seq(UCLASS_I2C, I2C_PWR, &bus);
+	if (ret) {
+		printf("Failed to get I2C_PWR\n");
+		return false;
+	}
+
+	/* V1.2 uses the TLA2024 at 0x49 instead of the STMPE811 at 0x41 */
+	ret = dm_i2c_probe(bus, 0x49, 0, &i2c_dev);
+
+	return (bool)!ret;
+}
+
+static void select_dt_from_module_version(void)
+{
+	if (is_som_variant_1_2())
+		env_set("variant", "-v1.2");
+	else
+		env_set("variant", "");
+}
+
 #ifdef CONFIG_BOARD_LATE_INIT
 int board_late_init(void)
 {
@@ -696,6 +725,8 @@ int board_late_init(void)
 	char env_str[256];
 	u32 rev;
 
+	select_dt_from_module_version();
+
 	rev = get_board_revision();
 	snprintf(env_str, ARRAY_SIZE(env_str), "%.4x", rev);
 	env_set("board_rev", env_str);

board/toradex/colibri_imx6/colibri_imx6.c

@@ -33,6 +33,7 @@
 #include <cpu.h>
 #include <dm/platform_data/serial_mxc.h>
 #include <fsl_esdhc_imx.h>
+#include <i2c.h>
 #include <imx_thermal.h>
 #include <miiphy.h>
 #include <netdev.h>
@@ -71,6 +72,8 @@ DECLARE_GLOBAL_DATA_PTR;
 
 #define OUTPUT_RGB (PAD_CTL_SPEED_MED|PAD_CTL_DSE_60ohm|PAD_CTL_SRE_FAST)
 
+#define I2C_PWR	1
+
 int dram_init(void)
 {
 	/* use the DDR controllers configured size */
@@ -609,6 +612,32 @@ int board_init(void)
 	return 0;
 }
 
+static bool is_som_variant_1_2(void)
+{
+	struct udevice *bus;
+	struct udevice *i2c_dev;
+	int ret;
+
+	ret = uclass_get_device_by_seq(UCLASS_I2C, I2C_PWR, &bus);
+	if (ret) {
+		printf("Failed to get I2C_PWR\n");
+		return false;
+	}
+
+	/* V1.2 uses the TLA2024 at 0x49 instead of the STMPE811 at 0x41 */
+	ret = dm_i2c_probe(bus, 0x49, 0, &i2c_dev);
+
+	return (bool)!ret;
+}
+
+static void select_dt_from_module_version(void)
+{
+	if (is_som_variant_1_2())
+		env_set("variant", "-v1.2");
+	else
+		env_set("variant", "");
+}
+
 #ifdef CONFIG_BOARD_LATE_INIT
 int board_late_init(void)
 {
@@ -616,6 +645,8 @@ int board_late_init(void)
 	char env_str[256];
 	u32 rev;
 
+	select_dt_from_module_version();
+
 	rev = get_board_revision();
 	snprintf(env_str, ARRAY_SIZE(env_str), "%.4x", rev);
 	env_set("board_rev", env_str);