Re: [PATCH 3/5] spi: pxa2xx: Detect number of enabled Intel LPSS SPI chip select signals

[Mark Brown <broonie@xxxxxxxxxx>]

The patch

   spi: pxa2xx: Detect number of enabled Intel LPSS SPI chip select signals

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 8b136baa5892f25bba0373d6eb0f5f84efc93986 Mon Sep 17 00:00:00 2001
From: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
Date: Wed, 28 Oct 2015 15:13:41 +0200
Subject: [PATCH] spi: pxa2xx: Detect number of enabled Intel LPSS SPI chip
 select signals

SPI capabilities register located in private registers space of newer
Intel LPSS SPI host controllers tell in register bits 12:9 which chip
select signals are enabled.

Use that information for detecting the number of chip selects. For
simplicity we assume chip selects are enabled one after another without
disabled chip selects between. For instance CS0 | CS1 | CS2 but not
CS0 | CS1 | CS3.

Signed-off-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
 drivers/spi/spi-pxa2xx.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index 040f6bb..a5c2dce 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -13,6 +13,7 @@
  * GNU General Public License for more details.
  */
 
+#include <linux/bitops.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/device.h>
@@ -66,6 +67,8 @@ MODULE_ALIAS("platform:pxa2xx-spi");
 #define LPSS_CS_CONTROL_CS_HIGH			BIT(1)
 #define LPSS_CS_CONTROL_CS_SEL_SHIFT		8
 #define LPSS_CS_CONTROL_CS_SEL_MASK		(3 << LPSS_CS_CONTROL_CS_SEL_SHIFT)
+#define LPSS_CAPS_CS_EN_SHIFT			9
+#define LPSS_CAPS_CS_EN_MASK			(0xf << LPSS_CAPS_CS_EN_SHIFT)
 
 struct lpss_config {
 	/* LPSS offset from drv_data->ioaddr */
@@ -74,6 +77,7 @@ struct lpss_config {
 	int reg_general;
 	int reg_ssp;
 	int reg_cs_ctrl;
+	int reg_capabilities;
 	/* FIFO thresholds */
 	u32 rx_threshold;
 	u32 tx_threshold_lo;
@@ -87,6 +91,7 @@ static const struct lpss_config lpss_platforms[] = {
 		.reg_general = 0x08,
 		.reg_ssp = 0x0c,
 		.reg_cs_ctrl = 0x18,
+		.reg_capabilities = -1,
 		.rx_threshold = 64,
 		.tx_threshold_lo = 160,
 		.tx_threshold_hi = 224,
@@ -96,6 +101,7 @@ static const struct lpss_config lpss_platforms[] = {
 		.reg_general = 0x08,
 		.reg_ssp = 0x0c,
 		.reg_cs_ctrl = 0x18,
+		.reg_capabilities = -1,
 		.rx_threshold = 64,
 		.tx_threshold_lo = 160,
 		.tx_threshold_hi = 224,
@@ -105,6 +111,7 @@ static const struct lpss_config lpss_platforms[] = {
 		.reg_general = -1,
 		.reg_ssp = 0x20,
 		.reg_cs_ctrl = 0x24,
+		.reg_capabilities = 0xfc,
 		.rx_threshold = 1,
 		.tx_threshold_lo = 32,
 		.tx_threshold_hi = 56,
@@ -1400,6 +1407,7 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
 	struct spi_master *master;
 	struct driver_data *drv_data;
 	struct ssp_device *ssp;
+	const struct lpss_config *config;
 	int status;
 	u32 tmp;
 
@@ -1439,7 +1447,6 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LOOP;
 
 	master->bus_num = ssp->port_id;
-	master->num_chipselect = platform_info->num_chipselect;
 	master->dma_alignment = DMA_ALIGNMENT;
 	master->cleanup = cleanup;
 	master->setup = setup;
@@ -1525,6 +1532,19 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
 	if (is_lpss_ssp(drv_data))
 		lpss_ssp_setup(drv_data);
 
+	if (is_lpss_ssp(drv_data)) {
+		lpss_ssp_setup(drv_data);
+		config = lpss_get_config(drv_data);
+		if (config->reg_capabilities >= 0) {
+			tmp = __lpss_ssp_read_priv(drv_data,
+						   config->reg_capabilities);
+			tmp &= LPSS_CAPS_CS_EN_MASK;
+			tmp >>= LPSS_CAPS_CS_EN_SHIFT;
+			platform_info->num_chipselect = ffz(tmp);
+		}
+	}
+	master->num_chipselect = platform_info->num_chipselect;
+
 	tasklet_init(&drv_data->pump_transfers, pump_transfers,
 		     (unsigned long)drv_data);
 
-- 
2.6.1

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