spi: pxa2xx: Prepare for new Intel LPSS SPI type

Some of the Intel LPSS SPI properties will be different in upcoming
platforms compared to existing Lynxpoint and BayTrail/Braswell. LPSS SPI
private registers will be at different offset and there will be changes in
individual registers and default FIFO thresholds too.

Add configuration for these differences and use them in runtime based on
LPSS SSP type. With this change private registers offset autodetection
becomes needless.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-pxa2xx.c

@@ -60,18 +60,51 @@ MODULE_ALIAS("platform:pxa2xx-spi");
 				| QUARK_X1000_SSCR1_TFT		\
 				| SSCR1_SPH | SSCR1_SPO | SSCR1_LBM)
 
-#define LPSS_RX_THRESH_DFLT	64
-#define LPSS_TX_LOTHRESH_DFLT	160
-#define LPSS_TX_HITHRESH_DFLT	224
-
-/* Offset from drv_data->lpss_base */
-#define GENERAL_REG		0x08
 #define GENERAL_REG_RXTO_HOLDOFF_DISABLE BIT(24)
-#define SSP_REG			0x0c
-#define SPI_CS_CONTROL		0x18
 #define SPI_CS_CONTROL_SW_MODE	BIT(0)
 #define SPI_CS_CONTROL_CS_HIGH	BIT(1)
 
+struct lpss_config {
+	/* LPSS offset from drv_data->ioaddr */
+	unsigned offset;
+	/* Register offsets from drv_data->lpss_base or -1 */
+	int reg_general;
+	int reg_ssp;
+	int reg_cs_ctrl;
+	/* FIFO thresholds */
+	u32 rx_threshold;
+	u32 tx_threshold_lo;
+	u32 tx_threshold_hi;
+};
+
+/* Keep these sorted with enum pxa_ssp_type */
+static const struct lpss_config lpss_platforms[] = {
+	{	/* LPSS_LPT_SSP */
+		.offset = 0x800,
+		.reg_general = 0x08,
+		.reg_ssp = 0x0c,
+		.reg_cs_ctrl = 0x18,
+		.rx_threshold = 64,
+		.tx_threshold_lo = 160,
+		.tx_threshold_hi = 224,
+	},
+	{	/* LPSS_BYT_SSP */
+		.offset = 0x400,
+		.reg_general = 0x08,
+		.reg_ssp = 0x0c,
+		.reg_cs_ctrl = 0x18,
+		.rx_threshold = 64,
+		.tx_threshold_lo = 160,
+		.tx_threshold_hi = 224,
+	},
+};
+
+static inline const struct lpss_config
+*lpss_get_config(const struct driver_data *drv_data)
+{
+	return &lpss_platforms[drv_data->ssp_type - LPSS_LPT_SSP];
+}
+
 static bool is_lpss_ssp(const struct driver_data *drv_data)
 {
 	switch (drv_data->ssp_type) {
@@ -198,63 +231,39 @@ static void __lpss_ssp_write_priv(struct driver_data *drv_data,
  */
 static void lpss_ssp_setup(struct driver_data *drv_data)
 {
-	unsigned offset = 0x400;
-	u32 value, orig;
+	const struct lpss_config *config;
+	u32 value;
 
-	/*
-	 * Perform auto-detection of the LPSS SSP private registers. They
-	 * can be either at 1k or 2k offset from the base address.
-	 */
-	orig = readl(drv_data->ioaddr + offset + SPI_CS_CONTROL);
-
-	/* Test SPI_CS_CONTROL_SW_MODE bit enabling */
-	value = orig | SPI_CS_CONTROL_SW_MODE;
-	writel(value, drv_data->ioaddr + offset + SPI_CS_CONTROL);
-	value = readl(drv_data->ioaddr + offset + SPI_CS_CONTROL);
-	if (value != (orig | SPI_CS_CONTROL_SW_MODE)) {
-		offset = 0x800;
-		goto detection_done;
-	}
-
-	orig = readl(drv_data->ioaddr + offset + SPI_CS_CONTROL);
-
-	/* Test SPI_CS_CONTROL_SW_MODE bit disabling */
-	value = orig & ~SPI_CS_CONTROL_SW_MODE;
-	writel(value, drv_data->ioaddr + offset + SPI_CS_CONTROL);
-	value = readl(drv_data->ioaddr + offset + SPI_CS_CONTROL);
-	if (value != (orig & ~SPI_CS_CONTROL_SW_MODE)) {
-		offset = 0x800;
-		goto detection_done;
-	}
-
-detection_done:
-	/* Now set the LPSS base */
-	drv_data->lpss_base = drv_data->ioaddr + offset;
+	config = lpss_get_config(drv_data);
+	drv_data->lpss_base = drv_data->ioaddr + config->offset;
 
 	/* Enable software chip select control */
 	value = SPI_CS_CONTROL_SW_MODE | SPI_CS_CONTROL_CS_HIGH;
-	__lpss_ssp_write_priv(drv_data, SPI_CS_CONTROL, value);
+	__lpss_ssp_write_priv(drv_data, config->reg_cs_ctrl, value);
 
 	/* Enable multiblock DMA transfers */
 	if (drv_data->master_info->enable_dma) {
-		__lpss_ssp_write_priv(drv_data, SSP_REG, 1);
+		__lpss_ssp_write_priv(drv_data, config->reg_ssp, 1);
 
-		value = __lpss_ssp_read_priv(drv_data, GENERAL_REG);
+		value = __lpss_ssp_read_priv(drv_data, config->reg_general);
 		value |= GENERAL_REG_RXTO_HOLDOFF_DISABLE;
-		__lpss_ssp_write_priv(drv_data, GENERAL_REG, value);
+		__lpss_ssp_write_priv(drv_data, config->reg_general, value);
 	}
 }
 
 static void lpss_ssp_cs_control(struct driver_data *drv_data, bool enable)
 {
+	const struct lpss_config *config;
 	u32 value;
 
-	value = __lpss_ssp_read_priv(drv_data, SPI_CS_CONTROL);
+	config = lpss_get_config(drv_data);
+
+	value = __lpss_ssp_read_priv(drv_data, config->reg_cs_ctrl);
 	if (enable)
 		value &= ~SPI_CS_CONTROL_CS_HIGH;
 	else
 		value |= SPI_CS_CONTROL_CS_HIGH;
-	__lpss_ssp_write_priv(drv_data, SPI_CS_CONTROL, value);
+	__lpss_ssp_write_priv(drv_data, config->reg_cs_ctrl, value);
 }
 
 static void cs_assert(struct driver_data *drv_data)
@@ -1081,6 +1090,7 @@ static int setup(struct spi_device *spi)
 {
 	struct pxa2xx_spi_chip *chip_info = NULL;
 	struct chip_data *chip;
+	const struct lpss_config *config;
 	struct driver_data *drv_data = spi_master_get_devdata(spi->master);
 	unsigned int clk_div;
 	uint tx_thres, tx_hi_thres, rx_thres;
@@ -1093,9 +1103,10 @@ static int setup(struct spi_device *spi)
 		break;
 	case LPSS_LPT_SSP:
 	case LPSS_BYT_SSP:
-		tx_thres = LPSS_TX_LOTHRESH_DFLT;
-		tx_hi_thres = LPSS_TX_HITHRESH_DFLT;
-		rx_thres = LPSS_RX_THRESH_DFLT;
+		config = lpss_get_config(drv_data);
+		tx_thres = config->tx_threshold_lo;
+		tx_hi_thres = config->tx_threshold_hi;
+		rx_thres = config->rx_threshold;
 		break;
 	default:
 		tx_thres = TX_THRESH_DFLT;

include/linux/pxa2xx_ssp.h

@@ -195,7 +195,7 @@ enum pxa_ssp_type {
 	PXA910_SSP,
 	CE4100_SSP,
 	QUARK_X1000_SSP,
-	LPSS_LPT_SSP,
+	LPSS_LPT_SSP, /* Keep LPSS types sorted with lpss_platforms[] */
 	LPSS_BYT_SSP,
 };