platform/x86: intel_pmc_core: Attach using APCI HID "INT33A1"

Most modern platforms already have the ACPI device "INT33A1" that could
be used to attach to the driver. Switch the driver to using that and
thus make the intel_pmc_core.c a pure platform_driver.

Some of the legacy platforms though, may still not have this ACPI device
in their ACPI tables. Thus for such platforms, move the code to manually
instantiate a platform_device into a new file of its own. This would
instantiate the intel_pmc_core platform device and thus attach to
the driver, if the ACPI device for the same ("INT33A1") is not present
in a system where it should be. This was discussed here:
https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1966991.html

Signed-off-by: Rajat Jain <rajatja@google.com>
[andy: renamed to intel_pmc_core_pltdrv.c to be in align with other drivers]
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/x86/Makefile

@@ -90,7 +90,7 @@ obj-$(CONFIG_INTEL_BXTWC_PMIC_TMU)	+= intel_bxtwc_tmu.o
 obj-$(CONFIG_INTEL_TELEMETRY)	+= intel_telemetry_core.o \
 				   intel_telemetry_pltdrv.o \
 				   intel_telemetry_debugfs.o
-obj-$(CONFIG_INTEL_PMC_CORE)    += intel_pmc_core.o
+obj-$(CONFIG_INTEL_PMC_CORE)    += intel_pmc_core.o intel_pmc_core_pltdrv.o
 obj-$(CONFIG_PMC_ATOM)		+= pmc_atom.o
 obj-$(CONFIG_MLX_PLATFORM)	+= mlx-platform.o
 obj-$(CONFIG_INTEL_TURBO_MAX_3) += intel_turbo_max_3.o

drivers/platform/x86/intel_pmc_core.c

@@ -1014,47 +1014,23 @@ static const struct dev_pm_ops pmc_core_pm_ops = {
 	SET_LATE_SYSTEM_SLEEP_PM_OPS(pmc_core_suspend, pmc_core_resume)
 };
 
+static const struct acpi_device_id pmc_core_acpi_ids[] = {
+	{"INT33A1", 0}, /* _HID for Intel Power Engine, _CID PNP0D80*/
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, pmc_core_acpi_ids);
+
 static struct platform_driver pmc_core_driver = {
 	.driver = {
 		.name = "intel_pmc_core",
+		.acpi_match_table = ACPI_PTR(pmc_core_acpi_ids),
 		.pm = &pmc_core_pm_ops,
 	},
 	.probe = pmc_core_probe,
 	.remove = pmc_core_remove,
 };
 
-static struct platform_device pmc_core_device = {
-	.name = "intel_pmc_core",
-};
-
-static int __init pmc_core_init(void)
-{
-	int ret;
-
-	if (!x86_match_cpu(intel_pmc_core_ids))
-		return -ENODEV;
-
-	ret = platform_driver_register(&pmc_core_driver);
-	if (ret)
-		return ret;
-
-	ret = platform_device_register(&pmc_core_device);
-	if (ret) {
-		platform_driver_unregister(&pmc_core_driver);
-		return ret;
-	}
-
-	return 0;
-}
-
-static void __exit pmc_core_exit(void)
-{
-	platform_device_unregister(&pmc_core_device);
-	platform_driver_unregister(&pmc_core_driver);
-}
-
-module_init(pmc_core_init)
-module_exit(pmc_core_exit)
+module_platform_driver(pmc_core_driver);
 
 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("Intel PMC Core Driver");

drivers/platform/x86/intel_pmc_core_pltdrv.c

@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Intel PMC Core platform init
+ * Copyright (c) 2019, Google Inc.
+ * Author - Rajat Jain
+ *
+ * This code instantiates platform devices for intel_pmc_core driver, only
+ * on supported platforms that may not have the ACPI devices in the ACPI tables.
+ * No new platforms should be added here, because we expect that new platforms
+ * should all have the ACPI device, which is the preferred way of enumeration.
+ */
+
+#include <linux/acpi.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#include <asm/cpu_device_id.h>
+#include <asm/intel-family.h>
+
+static struct platform_device pmc_core_device = {
+	.name = "intel_pmc_core",
+};
+
+/*
+ * intel_pmc_core_platform_ids is the list of platforms where we want to
+ * instantiate the platform_device if not already instantiated. This is
+ * different than intel_pmc_core_ids in intel_pmc_core.c which is the
+ * list of platforms that the driver supports for pmc_core device. The
+ * other list may grow, but this list should not.
+ */
+static const struct x86_cpu_id intel_pmc_core_platform_ids[] = {
+	INTEL_CPU_FAM6(SKYLAKE_MOBILE, pmc_core_device),
+	INTEL_CPU_FAM6(SKYLAKE_DESKTOP, pmc_core_device),
+	INTEL_CPU_FAM6(KABYLAKE_MOBILE, pmc_core_device),
+	INTEL_CPU_FAM6(KABYLAKE_DESKTOP, pmc_core_device),
+	INTEL_CPU_FAM6(CANNONLAKE_MOBILE, pmc_core_device),
+	INTEL_CPU_FAM6(ICELAKE_MOBILE, pmc_core_device),
+	{}
+};
+MODULE_DEVICE_TABLE(x86cpu, intel_pmc_core_platform_ids);
+
+static int __init pmc_core_platform_init(void)
+{
+	/* Skip creating the platform device if ACPI already has a device */
+	if (acpi_dev_present("INT33A1", NULL, -1))
+		return -ENODEV;
+
+	if (!x86_match_cpu(intel_pmc_core_platform_ids))
+		return -ENODEV;
+
+	return platform_device_register(&pmc_core_device);
+}
+
+static void __exit pmc_core_platform_exit(void)
+{
+	platform_device_unregister(&pmc_core_device);
+}
+
+module_init(pmc_core_platform_init);
+module_exit(pmc_core_platform_exit);
+MODULE_LICENSE("GPL v2");