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spi: pxa2xx: Add output control for multiple Intel LPSS chip selects 

Intel LPSS SPI host controllers in upcoming Intel platforms can have up
to 4 chip selects per port. Extend chip select control in
lpss_ssp_cs_control() by adding a code that selects the active chip
select output prior to changing the state. Detection for number of
enabled chip select signals will be added by another patch.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Jarkko Nikula 2015-10-28 15:13:40 +02:00 committed by Mark Brown
parent 624ea72ebd
commit d0283eb2db
1 changed files with 24 additions and 3 deletions
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27
drivers/spi/spi-pxa2xx.c
View File

@ -64,6 +64,8 @@ MODULE_ALIAS("platform:pxa2xx-spi");
#define LPSS_GENERAL_REG_RXTO_HOLDOFF_DISABLE BIT(24)
#define LPSS_CS_CONTROL_SW_MODE BIT(0)
#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)
struct lpss_config {
/* LPSS offset from drv_data->ioaddr */
@ -271,15 +273,34 @@ 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 <<= LPSS_CS_CONTROL_CS_SEL_SHIFT;
if (cs != (value & LPSS_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 &= ~LPSS_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 &= ~LPSS_CS_CONTROL_CS_HIGH;
else
} else {
value |= LPSS_CS_CONTROL_CS_HIGH;
}
__lpss_ssp_write_priv(drv_data, config->reg_cs_ctrl, value);
}