ACPI / LPSS: Ignore 10ms delay for Braswell

LPSS devices in Braswell does not need the default 10ms
d3_delay imposed by PCI specification. Removing this
unnecessary delay significantly reduces the resume time
approximately upto 200ms on this platform.
Signed-off-by: Srinidhi Kasagar <srinidhi.kasagar@intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_lpss.c

@@ -60,6 +60,7 @@ ACPI_MODULE_NAME("acpi_lpss");
 #define LPSS_CLK_DIVIDER		BIT(2)
 #define LPSS_LTR			BIT(3)
 #define LPSS_SAVE_CTX			BIT(4)
+#define LPSS_NO_D3_DELAY		BIT(5)
 
 struct lpss_private_data;
 
@@ -156,6 +157,10 @@ static const struct lpss_device_desc byt_pwm_dev_desc = {
 	.flags = LPSS_SAVE_CTX,
 };
 
+static const struct lpss_device_desc bsw_pwm_dev_desc = {
+	.flags = LPSS_SAVE_CTX | LPSS_NO_D3_DELAY,
+};
+
 static const struct lpss_device_desc byt_uart_dev_desc = {
 	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_SAVE_CTX,
 	.clk_con_id = "baudclk",
@@ -163,6 +168,14 @@ static const struct lpss_device_desc byt_uart_dev_desc = {
 	.setup = lpss_uart_setup,
 };
 
+static const struct lpss_device_desc bsw_uart_dev_desc = {
+	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_SAVE_CTX
+			| LPSS_NO_D3_DELAY,
+	.clk_con_id = "baudclk",
+	.prv_offset = 0x800,
+	.setup = lpss_uart_setup,
+};
+
 static const struct lpss_device_desc byt_spi_dev_desc = {
 	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_SAVE_CTX,
 	.prv_offset = 0x400,
@@ -178,8 +191,15 @@ static const struct lpss_device_desc byt_i2c_dev_desc = {
 	.setup = byt_i2c_setup,
 };
 
+static const struct lpss_device_desc bsw_i2c_dev_desc = {
+	.flags = LPSS_CLK | LPSS_SAVE_CTX | LPSS_NO_D3_DELAY,
+	.prv_offset = 0x800,
+	.setup = byt_i2c_setup,
+};
+
 static struct lpss_device_desc bsw_spi_dev_desc = {
-	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_SAVE_CTX,
+	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_SAVE_CTX
+			| LPSS_NO_D3_DELAY,
 	.prv_offset = 0x400,
 	.setup = lpss_deassert_reset,
 };
@@ -214,11 +234,12 @@ static const struct acpi_device_id acpi_lpss_device_ids[] = {
 	{ "INT33FC", },
 
 	/* Braswell LPSS devices */
-	{ "80862288", LPSS_ADDR(byt_pwm_dev_desc) },
-	{ "8086228A", LPSS_ADDR(byt_uart_dev_desc) },
+	{ "80862288", LPSS_ADDR(bsw_pwm_dev_desc) },
+	{ "8086228A", LPSS_ADDR(bsw_uart_dev_desc) },
 	{ "8086228E", LPSS_ADDR(bsw_spi_dev_desc) },
-	{ "808622C1", LPSS_ADDR(byt_i2c_dev_desc) },
+	{ "808622C1", LPSS_ADDR(bsw_i2c_dev_desc) },
 
+	/* Broadwell LPSS devices */
 	{ "INT3430", LPSS_ADDR(lpt_dev_desc) },
 	{ "INT3431", LPSS_ADDR(lpt_dev_desc) },
 	{ "INT3432", LPSS_ADDR(lpt_i2c_dev_desc) },
@@ -558,9 +579,14 @@ static void acpi_lpss_restore_ctx(struct device *dev,
 	 * The following delay is needed or the subsequent write operations may
 	 * fail. The LPSS devices are actually PCI devices and the PCI spec
 	 * expects 10ms delay before the device can be accessed after D3 to D0
-	 * transition.
+	 * transition. However some platforms like BSW does not need this delay.
 	 */
-	msleep(10);
+	unsigned int delay = 10;	/* default 10ms delay */
+
+	if (pdata->dev_desc->flags & LPSS_NO_D3_DELAY)
+		delay = 0;
+
+	msleep(delay);
 
 	for (i = 0; i < LPSS_PRV_REG_COUNT; i++) {
 		unsigned long offset = i * sizeof(u32);