Applied "spi: orion: On a38x, implement "50MHZ SPI AC timing" Erratum No. FE-9144572" to the spi tree

[Mark Brown <broonie@xxxxxxxxxx>]

The patch

   spi: orion: On a38x, implement "50MHZ SPI AC timing" Erratum No. FE-9144572

has been applied to the spi tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 38d6211e8565af5855385825a4fdc7261eb3740e Mon Sep 17 00:00:00 2001
From: Nadav Haklai <nadavh@xxxxxxxxxxx>
Date: Tue, 11 Aug 2015 11:58:47 +0200
Subject: [PATCH] spi: orion: On a38x, implement "50MHZ SPI AC timing" Erratum
 No. FE-9144572

Description:
On Armada 38x, the device SPI interface supports frequencies of up to
50 MHz. However, due to this erratum, when the device core clock is
250 MHz and the SPI interfaces is configured for 50MHz SPI clock and
CPOL=CPHA=1, there might occur data corruption on reads from the SPI
device.

Workaround:
Work in one of the following configurations:
1. Set CPOL=CPHA=0 in "SPI Interface Configuration Register".
2. Set TMISO_SAMPLE value to 0x2 in "SPI Timing Parameters 1 Register"
before setting the interface.

[gregory.clement@xxxxxxxxxxxxxxxxxx}: port to v4.2-rc, use
is_errata_50mhz_ac instead of using a new ARMADA_380_SPI spi type.

Signed-off-by: Nadav Haklai <nadavh@xxxxxxxxxxx>
Signed-off-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
 drivers/spi/spi-orion.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 53 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-orion.c b/drivers/spi/spi-orion.c
index 8cad107..a87cfd4 100644
--- a/drivers/spi/spi-orion.c
+++ b/drivers/spi/spi-orion.c
@@ -41,6 +41,11 @@
 #define ORION_SPI_DATA_OUT_REG		0x08
 #define ORION_SPI_DATA_IN_REG		0x0c
 #define ORION_SPI_INT_CAUSE_REG		0x10
+#define ORION_SPI_TIMING_PARAMS_REG	0x18
+
+#define ORION_SPI_TMISO_SAMPLE_MASK	(0x3 << 6)
+#define ORION_SPI_TMISO_SAMPLE_1	(1 << 6)
+#define ORION_SPI_TMISO_SAMPLE_2	(2 << 6)
 
 #define ORION_SPI_MODE_CPOL		(1 << 11)
 #define ORION_SPI_MODE_CPHA		(1 << 12)
@@ -70,6 +75,7 @@ struct orion_spi_dev {
 	unsigned int		min_divisor;
 	unsigned int		max_divisor;
 	u32			prescale_mask;
+	bool			is_errata_50mhz_ac;
 };
 
 struct orion_spi {
@@ -195,6 +201,41 @@ orion_spi_mode_set(struct spi_device *spi)
 	writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
 }
 
+static void
+orion_spi_50mhz_ac_timing_erratum(struct spi_device *spi, unsigned int speed)
+{
+	u32 reg;
+	struct orion_spi *orion_spi;
+
+	orion_spi = spi_master_get_devdata(spi->master);
+
+	/*
+	 * Erratum description: (Erratum NO. FE-9144572) The device
+	 * SPI interface supports frequencies of up to 50 MHz.
+	 * However, due to this erratum, when the device core clock is
+	 * 250 MHz and the SPI interfaces is configured for 50MHz SPI
+	 * clock and CPOL=CPHA=1 there might occur data corruption on
+	 * reads from the SPI device.
+	 * Erratum Workaround:
+	 * Work in one of the following configurations:
+	 * 1. Set CPOL=CPHA=0 in "SPI Interface Configuration
+	 * Register".
+	 * 2. Set TMISO_SAMPLE value to 0x2 in "SPI Timing Parameters 1
+	 * Register" before setting the interface.
+	 */
+	reg = readl(spi_reg(orion_spi, ORION_SPI_TIMING_PARAMS_REG));
+	reg &= ~ORION_SPI_TMISO_SAMPLE_MASK;
+
+	if (clk_get_rate(orion_spi->clk) == 250000000 &&
+			speed == 50000000 && spi->mode & SPI_CPOL &&
+			spi->mode & SPI_CPHA)
+		reg |= ORION_SPI_TMISO_SAMPLE_2;
+	else
+		reg |= ORION_SPI_TMISO_SAMPLE_1; /* This is the default value */
+
+	writel(reg, spi_reg(orion_spi, ORION_SPI_TIMING_PARAMS_REG));
+}
+
 /*
  * called only when no transfer is active on the bus
  */
@@ -216,6 +257,9 @@ orion_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
 
 	orion_spi_mode_set(spi);
 
+	if (orion_spi->devdata->is_errata_50mhz_ac)
+		orion_spi_50mhz_ac_timing_erratum(spi, speed);
+
 	rc = orion_spi_baudrate_set(spi, speed);
 	if (rc)
 		return rc;
@@ -413,6 +457,14 @@ static const struct orion_spi_dev armada_375_spi_dev_data = {
 	.prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
 };
 
+static const struct orion_spi_dev armada_380_spi_dev_data = {
+	.typ = ARMADA_SPI,
+	.max_hz = 50000000,
+	.max_divisor = 1920,
+	.prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
+	.is_errata_50mhz_ac = true,
+};
+
 static const struct of_device_id orion_spi_of_match_table[] = {
 	{
 		.compatible = "marvell,orion-spi",
@@ -428,7 +480,7 @@ static const struct of_device_id orion_spi_of_match_table[] = {
 	},
 	{
 		.compatible = "marvell,armada-380-spi",
-		.data = &armada_xp_spi_dev_data,
+		.data = &armada_380_spi_dev_data,
 	},
 	{
 		.compatible = "marvell,armada-390-spi",
-- 
2.5.0

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