A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-30 03:27:44 -04:00
Code Issues Projects Releases Packages Wiki Activity

mfd: cros ec: spi: Add delay for raising CS

Browse source 
The EC has specific timing it requires. Add support for an optional delay
after raising CS to fix timing issues. This is configurable based on
a DT property "google,cros-ec-spi-msg-delay".

If this property isn't set, then no delay will be added. However, if set
it will cause a delay equal to the value passed to it to be inserted at
the end of a transaction.

Signed-off-by: Rhyland Klein <[email protected]>
Reviewed-by: Bernie Thompson <[email protected]>
Reviewed-by: Andrew Bresticker <[email protected]>
Acked-by: Mark Rutland <[email protected]>
Signed-off-by: Thierry Reding <[email protected]>
Signed-off-by: Lee Jones <[email protected]>
This commit is contained in:
Rhyland Klein 2013-12-09 12:36:09 +01:00 • committed by Lee Jones
commit 01e73c89cf
2 changed files with 38 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

29
drivers/mfd/cros_ec_spi.c
View file

@ -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;