LPSS SPI devices in a successor of Intel Sunrisepoint can have up to 4 chip selects per port. SPI capabilities register bits 12:9 tell which are enabled. 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.
This patch adds support for detecting the number of enabled chip selects and adds output control to those LPSS SPI ports that have more than one chip select signal. Signed-off-by: Jarkko Nikula <[email protected]> --- drivers/spi/spi-pxa2xx.c | 48 +++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 43 insertions(+), 5 deletions(-) diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c index 672963653d3b..6851649d1b15 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> @@ -64,6 +65,10 @@ MODULE_ALIAS("platform:pxa2xx-spi"); #define GENERAL_REG_RXTO_HOLDOFF_DISABLE BIT(24) #define SPI_CS_CONTROL_SW_MODE BIT(0) #define SPI_CS_CONTROL_CS_HIGH BIT(1) +#define SPI_CS_CONTROL_CS_SEL_SHIFT 8 +#define SPI_CS_CONTROL_CS_SEL_MASK (3 << SPI_CS_CONTROL_CS_SEL_SHIFT) +#define SPI_CAPS_CS_EN_SHIFT 9 +#define SPI_CAPS_CS_EN_MASK (0xf << SPI_CAPS_CS_EN_SHIFT) struct lpss_config { /* LPSS offset from drv_data->ioaddr */ @@ -72,6 +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; @@ -85,6 +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, @@ -94,6 +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, @@ -103,6 +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, @@ -271,15 +280,34 @@ static void lpss_ssp_setup(struct driver_data *drv_data) static void lpss_ssp_cs_control(struct driver_data *drv_data, bool enable) { const struct lpss_config *config; - u32 value; + u32 value, cs; config = lpss_get_config(drv_data); value = __lpss_ssp_read_priv(drv_data, config->reg_cs_ctrl); - if (enable) + if (enable) { + cs = drv_data->cur_msg->spi->chip_select; + cs <<= SPI_CS_CONTROL_CS_SEL_SHIFT; + if (cs != (value & SPI_CS_CONTROL_CS_SEL_MASK)) { + /* + * When switching another chip select output active + * the output must be selected first and wait 2 ssp_clk + * cycles before changing state to active. Otherwise + * a short glitch will occur on the previous chip + * select since output select is latched but state + * control is not. + */ + value &= ~SPI_CS_CONTROL_CS_SEL_MASK; + value |= cs; + __lpss_ssp_write_priv(drv_data, + config->reg_cs_ctrl, value); + ndelay(1000000000 / + (drv_data->master->max_speed_hz / 2)); + } value &= ~SPI_CS_CONTROL_CS_HIGH; - else + } else { value |= SPI_CS_CONTROL_CS_HIGH; + } __lpss_ssp_write_priv(drv_data, config->reg_cs_ctrl, value); } @@ -1383,6 +1411,7 @@ 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; @@ -1422,7 +1451,6 @@ 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; @@ -1505,8 +1533,18 @@ static int pxa2xx_spi_probe(struct platform_device *pdev) if (!is_quark_x1000_ssp(drv_data)) pxa2xx_spi_write(drv_data, SSPSP, 0); - if (is_lpss_ssp(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 &= SPI_CAPS_CS_EN_MASK; + tmp >>= SPI_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 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
