diff options
| author | Vadim Bendebury <vbendeb@chromium.org> | 2017-02-23 08:53:53 -0800 |
|---|---|---|
| committer | Vadim Bendebury <vbendeb@chromium.org> | 2017-02-23 17:09:32 +0000 |
| commit | 569b5e8f0f124f08e2c1e3cab27081dfff2e266c (patch) | |
| tree | e0b6fa6bede92d69db88756cb171d977e848178d | |
| parent | 3cf2d9047ab798de9eb74ac73dcb3cd7b612f455 (diff) | |
| download | chrome-ec-569b5e8f0f124f08e2c1e3cab27081dfff2e266c.tar.gz | |
g: sps: add flow control signaling
The TPM SPI protocol adds flow control capability, but it is
impossible to enforce it by software, software implementations need
additional means of informing the master about the slave status.
Let's follow the i2c slave driver example and use the interrupt line
from the H1 to the SOC to generate a low level pulse every time
receive data processing is completed.
BRANCH=none
BUG=none
TEST=to benefit from this patch some changes on the SOC side will be
required.
Change-Id: I576233598e98e01a007dff6b973fd96ea5ea551c
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/446048
Reviewed-by: Mary Ruthven <mruthven@chromium.org>
| -rw-r--r-- | chip/g/sps.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/chip/g/sps.c b/chip/g/sps.c index 2496f7ed27..dba3129dfc 100644 --- a/chip/g/sps.c +++ b/chip/g/sps.c @@ -5,6 +5,7 @@ #include "common.h" #include "console.h" +#include "gpio.h" #include "hooks.h" #include "pmu.h" #include "registers.h" @@ -323,6 +324,14 @@ static void sps_rx_interrupt(uint32_t port, int cs_deasserted) if (cs_deasserted) sps_rx_handler(NULL, 0, 1); + + /* + * SPI does not provide inherent flow control. Let's use this pin to + * signal the AP that the device has finished processing received + * data. + */ + gpio_set_level(GPIO_INT_AP_L, 0); + gpio_set_level(GPIO_INT_AP_L, 1); } static void sps_cs_deassert_interrupt(uint32_t port) |