linux-kernel - [PATCH 2/2] ACPI / LPSS: Support for fractional divider clock

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Message-Id: <1398428541-912-3-git-send-email-heikki.krogerus@linux.intel.com>
Date:	Fri, 25 Apr 2014 15:22:21 +0300
From:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Mike Turquette <mturquette@...aro.org>
Cc:	Len Brown <lenb@...nel.org>,
	Mika Westerberg <mika.westerberg@...el.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Loic Poulain <loic.poulain@...el.com>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] ACPI / LPSS: Support for fractional divider clock

The dividers are available for UART and SPI on both
Lynxpoint and Baytrail. With SPI, handling the dividers is
optional, but in case of UART they should be adjusted
according to the requested baud rate.

Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
---
 drivers/acpi/acpi_lpss.c | 37 ++++++++++++++++++++++++++++++-------
 1 file changed, 30 insertions(+), 7 deletions(-)

diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
index 69e29f4..508ac9f 100644
--- a/drivers/acpi/acpi_lpss.c
+++ b/drivers/acpi/acpi_lpss.c
@@ -58,6 +58,7 @@ struct lpss_device_desc {
 	unsigned int prv_offset;
 	size_t prv_size_override;
 	bool clk_gate;
+	bool clk_divider;
 	struct lpss_shared_clock *shared_clock;
 	void (*setup)(struct lpss_private_data *pdata);
 };
@@ -119,16 +120,11 @@ static struct lpss_device_desc byt_pwm_dev_desc = {
 	.shared_clock = &pwm_clock,
 };
 
-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,
+	.clk_divider = true,
 	.setup = lpss_uart_setup,
 };
 
@@ -246,8 +242,35 @@ static int register_device_clock(struct acpi_device *adev,
 		parent = shared_clock->name;
 	}
 
+	if (dev_desc->clk_divider) {
+		char *name = kzalloc(strlen(dev_name(&adev->dev)) + 8,
+				     GFP_KERNEL);
+		if (!name)
+			return -ENOMEM;
+		strcpy(name, "div_clk-");
+		strcat(name, dev_name(&adev->dev));
+
+		clk = clk_register_fractional_divider(NULL, name, parent, 0,
+					pdata->mmio_base + dev_desc->prv_offset,
+					1, 15, 16, 15, 0, NULL);
+		parent = name;
+
+		name = kzalloc(strlen(dev_name(&adev->dev)) + 11, GFP_KERNEL);
+		if (!name)
+			return -ENOMEM;
+		strcpy(name, "clk_update-");
+		strcat(name, dev_name(&adev->dev));
+
+		clk = clk_register_gate(NULL, name, parent,
+					CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE,
+					pdata->mmio_base + dev_desc->prv_offset,
+					31, 0, NULL);
+		parent = name;
+	}
+
 	if (dev_desc->clk_gate) {
-		clk = clk_register_gate(NULL, dev_name(&adev->dev), parent, 0,
+		clk = clk_register_gate(NULL, dev_name(&adev->dev), parent,
+					CLK_SET_RATE_PARENT,
 					pdata->mmio_base + dev_desc->prv_offset,
 					0, 0, NULL);
 		pdata->clk = clk;
-- 
2.0.0.rc0

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