[PATCH] spi: vulcan: Add ACPI support for SPI driver

[PATCH] spi: vulcan: Add ACPI support for SPI driver

[kamlakant.patel-dY08KVG/lbpWk0Htik3J/w]

From: Kamlakant Patel <kamlakant.patel-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>

Add ACPI support for SPI controller driver on Broadcom Vulcan ARM64
plateform.

Signed-off-by: Kamlakant Patel <kamlakant.patel-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
---
 drivers/spi/spi-xlp.c |   33 ++++++++++++++++++++++++++++-----
 1 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/drivers/spi/spi-xlp.c b/drivers/spi/spi-xlp.c
index 8f04fec..7494254 100644
--- a/drivers/spi/spi-xlp.c
+++ b/drivers/spi/spi-xlp.c
@@ -11,6 +11,7 @@
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  */
+#include <linux/acpi.h>
 #include <linux/clk.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -85,7 +86,7 @@
 #define XLP_SPI_TXRXTH			0x80
 #define XLP_SPI_FIFO_SIZE		8
 #define XLP_SPI_MAX_CS			4
-#define XLP_SPI_DEFAULT_FREQ		133333333
+#define VULCAN_SPI_DEFAULT_FREQ		133000000
 #define XLP_SPI_FDIV_MIN		4
 #define XLP_SPI_FDIV_MAX		65535
 /*
@@ -403,11 +404,24 @@ static int xlp_spi_probe(struct platform_device *pdev)
 	}
 
 	clk = devm_clk_get(&pdev->dev, NULL);
-	if (IS_ERR(clk)) {
-		dev_err(&pdev->dev, "could not get spi clock\n");
-		return -ENODEV;
+	if (!IS_ERR(clk)) {
+		xspi->spi_clk = clk_get_rate(clk);
+	} else {
+		u32 freq;
+
+		err = device_property_read_u32(&pdev->dev,
+					"clock-frequency", &freq);
+		if (err) {
+			/*
+			 * Use default SPI frequency for Vulcan unless
+			 * changed by firmaware.
+			 */
+			dev_err(&pdev->dev, "Can't get clock-frequency,
+						using default\n");
+			freq = VULCAN_SPI_DEFAULT_FREQ;
+		}
+		xspi->spi_clk = freq;
 	}
-	xspi->spi_clk = clk_get_rate(clk);
 
 	master = spi_alloc_master(&pdev->dev, 0);
 	if (!master) {
@@ -437,6 +451,14 @@ static int xlp_spi_probe(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id xlp_spi_acpi_match[] = {
+	{ "BRCM900D", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(acpi, xlp_spi_acpi_match);
+#endif
+
 static const struct of_device_id xlp_spi_dt_id[] = {
 	{ .compatible = "netlogic,xlp832-spi" },
 	{ },
@@ -447,6 +469,7 @@ static struct platform_driver xlp_spi_driver = {
 	.driver = {
 		.name	= "xlp-spi",
 		.of_match_table = xlp_spi_dt_id,
+		.acpi_match_table = ACPI_PTR(xlp_spi_acpi_match),
 	},
 };
 module_platform_driver(xlp_spi_driver);
-- 
1.7.1

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Re: [PATCH] spi: vulcan: Add ACPI support for SPI driver

[Mark Brown]

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On Tue, Jul 26, 2016 at 10:52:06AM +0530, kamlakant.patel-dY08KVG/lbpWk0Htik3J/w@public.gmane.org wrote:

> -	if (IS_ERR(clk)) {
> -		dev_err(&pdev->dev, "could not get spi clock\n");
> -		return -ENODEV;
> +	if (!IS_ERR(clk)) {
> +		xspi->spi_clk = clk_get_rate(clk);
> +	} else {
> +		u32 freq;
> +
> +		err = device_property_read_u32(&pdev->dev,
> +					"clock-frequency", &freq);

Ugh, this is horrible, especially with...

> +		if (err) {
> +			/*
> +			 * Use default SPI frequency for Vulcan unless
> +			 * changed by firmaware.
> +			 */
> +			dev_err(&pdev->dev, "Can't get clock-frequency,
> +						using default\n");
> +			freq = VULCAN_SPI_DEFAULT_FREQ;

...this just completely ignoring error handling (it at least needs
fixing for probe deferral).  This actively breaks things for existing
users of the driver.  Splitting the log message up like that is also
very bad, the log message will end up with a newline and a huge number
of spaces in the middle of it.

This should be specific to the relevant systems, not unconditionally
changed for all users, and should be implemented by registering a fixed
clock on the relevant platforms like spi-pxa2xx does on Intel systems so
that the driver works in the same manner outside of probe on everything.

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