diff options
Diffstat (limited to 'drivers/mfd')
| -rw-r--r-- | drivers/mfd/cros_ec_spi.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c index 005403643539..84af8d7a4295 100644 --- a/drivers/mfd/cros_ec_spi.c +++ b/drivers/mfd/cros_ec_spi.c @@ -18,6 +18,7 @@ #include <linux/module.h> #include <linux/mfd/cros_ec.h> #include <linux/mfd/cros_ec_commands.h> +#include <linux/of.h> #include <linux/platform_device.h> #include <linux/slab.h> #include <linux/spi/spi.h> @@ -62,10 +63,13 @@ * @spi: SPI device we are connected to * @last_transfer_ns: time that we last finished a transfer, or 0 if there * if no record + * @end_of_msg_delay: used to set the delay_usecs on the spi_transfer that + * is sent when we want to turn off CS at the end of a transaction. */ struct cros_ec_spi { struct spi_device *spi; s64 last_transfer_ns; + unsigned int end_of_msg_delay; }; static void debug_packet(struct device *dev, const char *name, u8 *ptr, @@ -238,6 +242,17 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev, /* turn off CS */ spi_message_init(&msg); + + if (ec_spi->end_of_msg_delay) { + /* + * Add delay for last transaction, to ensure the rising edge + * doesn't come too soon after the end of the data. + */ + memset(&trans, 0, sizeof(trans)); + trans.delay_usecs = ec_spi->end_of_msg_delay; + spi_message_add_tail(&trans, &msg); + } + final_ret = spi_sync(ec_spi->spi, &msg); ktime_get_ts(&ts); ec_spi->last_transfer_ns = timespec_to_ns(&ts); @@ -284,6 +299,17 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev, return 0; } +static void cros_ec_spi_dt_probe(struct cros_ec_spi *ec_spi, struct device *dev) +{ + struct device_node *np = dev->of_node; + u32 val; + int ret; + + ret = of_property_read_u32(np, "google,cros-ec-spi-msg-delay", &val); + if (!ret) + ec_spi->end_of_msg_delay = val; +} + static int cros_ec_spi_probe(struct spi_device *spi) { struct device *dev = &spi->dev; @@ -305,6 +331,9 @@ static int cros_ec_spi_probe(struct spi_device *spi) if (!ec_dev) return -ENOMEM; + /* Check for any DT properties */ + cros_ec_spi_dt_probe(ec_spi, dev); + spi_set_drvdata(spi, ec_dev); ec_dev->name = "SPI"; ec_dev->dev = dev; |