ACPI / LPSS: add support for Intel BayTrail

Intel BayTrail has almost the same Low Power Subsystem than Lynxpoint with
few differences. Peripherals are clocked with different speeds (typically
lower) and the clock is not always gated. To support this we add
possibility to share a common fixed rate clock and make clock gating
optional.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_lpss.c

@@ -33,11 +33,19 @@ ACPI_MODULE_NAME("acpi_lpss");
 #define LPSS_SW_LTR			0x10
 #define LPSS_AUTO_LTR			0x14
 
+struct lpss_shared_clock {
+	const char *name;
+	unsigned long rate;
+	struct clk *clk;
+};
+
 struct lpss_device_desc {
 	bool clk_required;
 	const char *clkdev_name;
 	bool ltr_required;
 	unsigned int prv_offset;
+	bool clk_gate;
+	struct lpss_shared_clock *shared_clock;
 };
 
 static struct lpss_device_desc lpss_dma_desc = {
@@ -56,6 +64,7 @@ static struct lpss_device_desc lpt_dev_desc = {
 	.clk_required = true,
 	.prv_offset = 0x800,
 	.ltr_required = true,
+	.clk_gate = true,
 };
 
 static struct lpss_device_desc lpt_sdio_dev_desc = {
@@ -63,6 +72,45 @@ static struct lpss_device_desc lpt_sdio_dev_desc = {
 	.ltr_required = true,
 };
 
+static struct lpss_shared_clock uart_clock = {
+	.name = "uart_clk",
+	.rate = 44236800,
+};
+
+static struct lpss_device_desc byt_uart_dev_desc = {
+	.clk_required = true,
+	.prv_offset = 0x800,
+	.clk_gate = true,
+	.shared_clock = &uart_clock,
+};
+
+static struct lpss_shared_clock spi_clock = {
+	.name = "spi_clk",
+	.rate = 50000000,
+};
+
+static struct lpss_device_desc byt_spi_dev_desc = {
+	.clk_required = true,
+	.prv_offset = 0x400,
+	.clk_gate = true,
+	.shared_clock = &spi_clock,
+};
+
+static struct lpss_device_desc byt_sdio_dev_desc = {
+	.clk_required = true,
+};
+
+static struct lpss_shared_clock i2c_clock = {
+	.name = "i2c_clk",
+	.rate = 100000000,
+};
+
+static struct lpss_device_desc byt_i2c_dev_desc = {
+	.clk_required = true,
+	.prv_offset = 0x800,
+	.shared_clock = &i2c_clock,
+};
+
 static const struct acpi_device_id acpi_lpss_device_ids[] = {
 	/* Generic LPSS devices */
 	{ "INTL9C60", (unsigned long)&lpss_dma_desc },
@@ -77,6 +125,13 @@ static const struct acpi_device_id acpi_lpss_device_ids[] = {
 	{ "INT33C6", (unsigned long)&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 },
+	{ "INT33B2", },
+
 	{ }
 };
 
@@ -98,7 +153,10 @@ static int register_device_clock(struct acpi_device *adev,
 				 struct lpss_private_data *pdata)
 {
 	const struct lpss_device_desc *dev_desc = pdata->dev_desc;
+	struct lpss_shared_clock *shared_clock = dev_desc->shared_clock;
+	struct clk *clk = ERR_PTR(-ENODEV);
 	struct lpss_clk_data *clk_data;
+	const char *parent;
 
 	if (!lpss_clk_dev)
 		lpt_register_clock_device();
@@ -117,14 +175,30 @@ static int register_device_clock(struct acpi_device *adev,
 	    || pdata->mmio_size < dev_desc->prv_offset + LPSS_CLK_SIZE)
 		return -ENODATA;
 
-	pdata->clk = clk_register_gate(NULL, dev_name(&adev->dev),
-				       clk_data->name, 0,
+	parent = clk_data->name;
+
+	if (shared_clock) {
+		clk = shared_clock->clk;
+		if (!clk) {
+			clk = clk_register_fixed_rate(NULL, shared_clock->name,
+						      "lpss_clk", 0,
+						      shared_clock->rate);
+			shared_clock->clk = clk;
+		}
+		parent = shared_clock->name;
+	}
+
+	if (dev_desc->clk_gate) {
+		clk = clk_register_gate(NULL, dev_name(&adev->dev), parent, 0,
 					pdata->mmio_base + dev_desc->prv_offset,
 					0, 0, NULL);
-	if (IS_ERR(pdata->clk))
-		return PTR_ERR(pdata->clk);
+		pdata->clk = clk;
+	}
 
-	clk_register_clkdev(pdata->clk, NULL, dev_name(&adev->dev));
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	clk_register_clkdev(clk, NULL, dev_name(&adev->dev));
 	return 0;
 }
 

drivers/clk/x86/clk-lpt.c

@@ -1,5 +1,5 @@
 /*
- * Intel Lynxpoint LPSS clocks.
+ * Intel Low Power Subsystem clocks.
  *
  * Copyright (C) 2013, Intel Corporation
  * Authors: Mika Westerberg <mika.westerberg@linux.intel.com>
@@ -18,8 +18,6 @@
 #include <linux/platform_data/clk-lpss.h>
 #include <linux/platform_device.h>
 
-#define PRV_CLOCK_PARAMS 0x800
-
 static int lpt_clk_probe(struct platform_device *pdev)
 {
 	struct lpss_clk_data *drvdata;