[PATCH V4 08/11] ACPI: introduce dummy lpss scan handler

[Zhang Rui]

When the lpss scan handler is compiled out, aka, CONFIG_X86_INTEL_LPSS
is cleared, those ACPI device objects will be recgonized as regular
_HID devices, and a platform device would be created for each of them.
This is wrong because the platform drivers for those devices would
be loaded, but with broken behavior.

In order to fix this, a dummy lpss scan handler is introduced
to prevent those platform devices from being created.
Plus, if lpt_clk_init() fails, we need this dummy scan handler as well.

Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
---
 drivers/acpi/Makefile    |    2 +-
 drivers/acpi/acpi_lpss.c |   66 +++++++++++++++++++++++++++++++++-------------
 drivers/acpi/internal.h  |    4 ---
 3 files changed, 48 insertions(+), 24 deletions(-)

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 9a43893..2173e30 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -39,7 +39,7 @@ acpi-y				+= processor_core.o
 acpi-y				+= ec.o
 acpi-$(CONFIG_ACPI_DOCK)	+= dock.o
 acpi-y				+= pci_root.o pci_link.o pci_irq.o
-acpi-$(CONFIG_X86_INTEL_LPSS)	+= acpi_lpss.o
+acpi-y				+= acpi_lpss.o
 acpi-y				+= acpi_platform.o
 acpi-y				+= acpi_pnp.o
 acpi-y				+= power.o
diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
index 6745fe1..cfbf2c0 100644
--- a/drivers/acpi/acpi_lpss.c
+++ b/drivers/acpi/acpi_lpss.c
@@ -24,6 +24,8 @@
 
 ACPI_MODULE_NAME("acpi_lpss");
 
+#ifdef CONFIG_X86_INTEL_LPSS
+
 #define LPSS_CLK_SIZE	0x04
 #define LPSS_LTR_SIZE	0x18
 
@@ -142,39 +144,48 @@ static struct lpss_device_desc byt_i2c_dev_desc = {
 	.shared_clock = &i2c_clock,
 };
 
+#define LPSS_PTR(desc) ((unsigned long)&desc)
+
+#else
+
+#define LPSS_PTR(desc) 0
+
+#endif
+
 static const struct acpi_device_id acpi_lpss_device_ids[] = {
 	/* Generic LPSS devices */
-	{ "INTL9C60", (unsigned long)&lpss_dma_desc },
+	{ "INTL9C60", LPSS_PTR(lpss_dma_desc) },
 
 	/* Lynxpoint LPSS devices */
-	{ "INT33C0", (unsigned long)&lpt_dev_desc },
-	{ "INT33C1", (unsigned long)&lpt_dev_desc },
-	{ "INT33C2", (unsigned long)&lpt_dev_desc },
-	{ "INT33C3", (unsigned long)&lpt_dev_desc },
-	{ "INT33C4", (unsigned long)&lpt_uart_dev_desc },
-	{ "INT33C5", (unsigned long)&lpt_uart_dev_desc },
-	{ "INT33C6", (unsigned long)&lpt_sdio_dev_desc },
+	{ "INT33C0", LPSS_PTR(lpt_dev_desc) },
+	{ "INT33C1", LPSS_PTR(lpt_dev_desc) },
+	{ "INT33C2", LPSS_PTR(lpt_dev_desc) },
+	{ "INT33C3", LPSS_PTR(lpt_dev_desc) },
+	{ "INT33C4", LPSS_PTR(lpt_uart_dev_desc) },
+	{ "INT33C5", LPSS_PTR(lpt_uart_dev_desc) },
+	{ "INT33C6", LPSS_PTR(lpt_sdio_dev_desc) },
 	{ "INT33C7", },
 
 	/* BayTrail LPSS devices */
-	{ "80860F0A", (unsigned long)&byt_uart_dev_desc },
-	{ "80860F0E", (unsigned long)&byt_spi_dev_desc },
-	{ "80860F14", (unsigned long)&byt_sdio_dev_desc },
-	{ "80860F41", (unsigned long)&byt_i2c_dev_desc },
+	{ "80860F0A", LPSS_PTR(byt_uart_dev_desc) },
+	{ "80860F0E", LPSS_PTR(byt_spi_dev_desc) },
+	{ "80860F14", LPSS_PTR(byt_sdio_dev_desc) },
+	{ "80860F41", LPSS_PTR(byt_i2c_dev_desc) },
 	{ "INT33B2", },
 
-	{ "INT3430", (unsigned long)&lpt_dev_desc },
-	{ "INT3431", (unsigned long)&lpt_dev_desc },
-	{ "INT3432", (unsigned long)&lpt_dev_desc },
-	{ "INT3433", (unsigned long)&lpt_dev_desc },
-	{ "INT3434", (unsigned long)&lpt_uart_dev_desc },
-	{ "INT3435", (unsigned long)&lpt_uart_dev_desc },
-	{ "INT3436", (unsigned long)&lpt_sdio_dev_desc },
+	{ "INT3430", LPSS_PTR(lpt_dev_desc) },
+	{ "INT3431", LPSS_PTR(lpt_dev_desc) },
+	{ "INT3432", LPSS_PTR(lpt_dev_desc) },
+	{ "INT3433", LPSS_PTR(lpt_dev_desc) },
+	{ "INT3434", LPSS_PTR(lpt_uart_dev_desc) },
+	{ "INT3435", LPSS_PTR(lpt_uart_dev_desc) },
+	{ "INT3436", LPSS_PTR(lpt_sdio_dev_desc) },
 	{ "INT3437", },
 
 	{ }
 };
 
+#ifdef CONFIG_X86_INTEL_LPSS
 static int is_memory(struct acpi_resource *res, void *not_used)
 {
 	struct resource r;
@@ -431,10 +442,27 @@ static struct acpi_scan_handler lpss_handler = {
 	.attach = acpi_lpss_create_device,
 };
 
+#endif /* CONFIG_X86_INTEL_LPSS */
+
+static int acpi_lpss_dummy_attach(struct acpi_device *adev,
+				const struct acpi_device_id *id)
+{
+	return 1;
+}
+
+static struct acpi_scan_handler lpss_dummy_handler = {
+	.ids = acpi_lpss_device_ids,
+	.attach = acpi_lpss_dummy_attach,
+};
+
 void __init acpi_lpss_init(void)
 {
+#ifdef CONFIG_X86_INTEL_LPSS
 	if (!lpt_clk_init()) {
 		bus_register_notifier(&platform_bus_type, &acpi_lpss_nb);
 		acpi_scan_add_handler(&lpss_handler);
+		return;
 	}
+#endif
+	acpi_scan_add_handler(&lpss_dummy_handler);
 }
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 74ea3f1..a0c9368 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -67,11 +67,7 @@ int acpi_debugfs_init(void);
 #else
 static inline void acpi_debugfs_init(void) { return; }
 #endif
-#ifdef CONFIG_X86_INTEL_LPSS
 void acpi_lpss_init(void);
-#else
-static inline void acpi_lpss_init(void) {}
-#endif
 
 bool acpi_queue_hotplug_work(struct work_struct *work);
 bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent);
-- 
1.7.9.5

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