linux-kernel - [PATCH 3/3] ACPI: create Lynxpoint clocks if LPSS devices are found during scan

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Date:	Mon, 14 Jan 2013 16:46:28 +0200
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	linux-kernel@...r.kernel.org
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Len Brown <lenb@...nel.org>, "Rafael J. Wysocki" <rjw@...k.pl>,
	Mike Turquette <mturquette@...aro.org>,
	Arnd Bergmann <arnd@...db.de>,
	Linus Walleij <linus.walleij@...aro.org>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	linux-acpi@...r.kernel.org
Subject: [PATCH 3/3] ACPI: create Lynxpoint clocks if LPSS devices are found during scan

Since we don't want to create the Lynxpoint LPSS clock tree on a machines
where no LPSS exists at all we look for the Lynxpoint device ACPI HIDs
during ACPI namespace scan and if a known device is seen we assume that it
is safe to create the LPSS clocks.

Therefore we allow init function to be passed via acpi_platform_device_ids[]
table which is called whenever the corresponding device is found.

Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
---
 drivers/acpi/scan.c |   36 +++++++++++++++++++++++++++---------
 1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 6a12702..8d9965e 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -11,6 +11,7 @@
 #include <linux/kthread.h>
 #include <linux/dmi.h>
 #include <linux/nls.h>
+#include <linux/platform_device.h>
 
 #include <acpi/acpi_drivers.h>
 
@@ -29,6 +30,15 @@ extern struct acpi_device *acpi_root;
 
 static const char *dummy_hid = "device";
 
+static void lpt_lpss_init_once(void)
+{
+	static struct platform_device *pdev;
+
+	/* Lynxpoint LPSS clocks */
+	if (!pdev)
+		pdev = platform_device_register_simple("clk-lpt", -1, NULL, 0);
+}
+
 /*
  * The following ACPI IDs are known to be suitable for representing as
  * platform devices.
@@ -38,14 +48,14 @@ static const struct acpi_device_id acpi_platform_device_ids[] = {
 	{ "PNP0D40" },
 
 	/* Haswell LPSS devices */
-	{ "INT33C0", 0 },
-	{ "INT33C1", 0 },
-	{ "INT33C2", 0 },
-	{ "INT33C3", 0 },
-	{ "INT33C4", 0 },
-	{ "INT33C5", 0 },
-	{ "INT33C6", 0 },
-	{ "INT33C7", 0 },
+	{ "INT33C0", (kernel_ulong_t)lpt_lpss_init_once },
+	{ "INT33C1", (kernel_ulong_t)lpt_lpss_init_once },
+	{ "INT33C2", (kernel_ulong_t)lpt_lpss_init_once },
+	{ "INT33C3", (kernel_ulong_t)lpt_lpss_init_once },
+	{ "INT33C4", (kernel_ulong_t)lpt_lpss_init_once },
+	{ "INT33C5", (kernel_ulong_t)lpt_lpss_init_once },
+	{ "INT33C6", (kernel_ulong_t)lpt_lpss_init_once },
+	{ "INT33C7", (kernel_ulong_t)lpt_lpss_init_once },
 
 	{ }
 };
@@ -1580,6 +1590,7 @@ static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
 static acpi_status acpi_bus_device_attach(acpi_handle handle, u32 lvl_not_used,
 					  void *not_used, void **ret_not_used)
 {
+	const struct acpi_device_id *id;
 	acpi_status status = AE_OK;
 	struct acpi_device *device;
 	unsigned long long sta_not_used;
@@ -1595,7 +1606,14 @@ static acpi_status acpi_bus_device_attach(acpi_handle handle, u32 lvl_not_used,
 	if (acpi_bus_get_device(handle, &device))
 		return AE_CTRL_DEPTH;
 
-	if (!acpi_match_device_ids(device, acpi_platform_device_ids)) {
+	id = __acpi_match_device(device, acpi_platform_device_ids);
+	if (id) {
+		void (*init)(void) = (void (*)(void))id->driver_data;
+
+		/* Run any initialization if required */
+		if (init)
+			init();
+
 		/* This is a known good platform device. */
 		acpi_create_platform_device(device);
 	} else if (device_attach(&device->dev) < 0) {
-- 
1.7.10.4

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