ACPI / PMIC: Add Cherry Trail Crystal Cove PMIC OpRegion driver

We have no docs for the CHT Crystal Cove PMIC. The Asus Zenfone-2 kernel
code has 2 Crystal Cove regulator drivers, one calls the PMIC a "Crystal
Cove Plus" PMIC and talks about Cherry Trail, so presuambly that one
could be used to get register info for the regulators if we need to
implement regulator support in the future.

For now the sole purpose of this driver is to make
intel_soc_pmic_exec_mipi_pmic_seq_element work on devices with a
CHT Crystal Cove PMIC.

Specifically this fixes the following MIPI PMIC sequence related errors
on e.g. an Asus T100HA:

[ 178.211801] intel_soc_pmic_exec_mipi_pmic_seq_element: No PMIC registered
[ 178.211897] [drm:intel_dsi_dcs_init_backlight_funcs [i915]] *ERROR* mipi_exec_pmic failed, error: -6

Signed-off-by: Hans de Goede <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/acpi/Kconfig

···
 	  This config adds ACPI operation region support for the Bay Trail
 	  version of the Crystal Cove PMIC.
 
+config CHTCRC_PMIC_OPREGION
+	bool "ACPI operation region support for Cherry Trail Crystal Cove PMIC"
+	depends on INTEL_SOC_PMIC
+	help
+	  This config adds ACPI operation region support for the Cherry Trail
+	  version of the Crystal Cove PMIC.
+
 config XPOWER_PMIC_OPREGION
 	bool "ACPI operation region support for XPower AXP288 PMIC"
 	depends on MFD_AXP20X_I2C && IOSF_MBI=y

drivers/acpi/Makefile

···
 
 obj-$(CONFIG_PMIC_OPREGION)	+= pmic/intel_pmic.o
 obj-$(CONFIG_BYTCRC_PMIC_OPREGION) += pmic/intel_pmic_bytcrc.o
+obj-$(CONFIG_CHTCRC_PMIC_OPREGION) += pmic/intel_pmic_chtcrc.o
 obj-$(CONFIG_XPOWER_PMIC_OPREGION) += pmic/intel_pmic_xpower.o
 obj-$(CONFIG_BXT_WC_PMIC_OPREGION) += pmic/intel_pmic_bxtwc.o
 obj-$(CONFIG_CHT_WC_PMIC_OPREGION) += pmic/intel_pmic_chtwc.o

drivers/acpi/pmic/intel_pmic_chtcrc.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Intel Cherry Trail Crystal Cove PMIC operation region driver
+ *
+ * Copyright (C) 2019 Hans de Goede <[e-mail]>
+ */
+
+#include <linux/acpi.h>
+#include <linux/init.h>
+#include <linux/mfd/intel_soc_pmic.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include "intel_pmic.h"
+
+/*
+ * We have no docs for the CHT Crystal Cove PMIC. The Asus Zenfone-2 kernel
+ * code has 2 Crystal Cove regulator drivers, one calls the PMIC a "Crystal
+ * Cove Plus" PMIC and talks about Cherry Trail, so presuambly that one
+ * could be used to get register info for the regulators if we need to
+ * implement regulator support in the future.
+ *
+ * For now the sole purpose of this driver is to make
+ * intel_soc_pmic_exec_mipi_pmic_seq_element work on devices with a
+ * CHT Crystal Cove PMIC.
+ */
+static struct intel_pmic_opregion_data intel_chtcrc_pmic_opregion_data = {
+	.pmic_i2c_address = 0x6e,
+};
+
+static int intel_chtcrc_pmic_opregion_probe(struct platform_device *pdev)
+{
+	struct intel_soc_pmic *pmic = dev_get_drvdata(pdev->dev.parent);
+	return intel_pmic_install_opregion_handler(&pdev->dev,
+			ACPI_HANDLE(pdev->dev.parent), pmic->regmap,
+			&intel_chtcrc_pmic_opregion_data);
+}
+
+static struct platform_driver intel_chtcrc_pmic_opregion_driver = {
+	.probe = intel_chtcrc_pmic_opregion_probe,
+	.driver = {
+		.name = "cht_crystal_cove_pmic",
+	},
+};
+builtin_platform_driver(intel_chtcrc_pmic_opregion_driver);