This allows to drive MCU RST lines or similar with the ch341a
during a flashrom run. CS1 is active low and CS2 is active high;
note that the tristate state is a weak pullup, thus using
CS2 would need an external pull-down.
Signed-off-by: Urja Rannikko <urja...@gmail.com>
---
ch341a_spi.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/ch341a_spi.c b/ch341a_spi.c
index 6eb2804..80717f8 100644
--- a/ch341a_spi.c
+++ b/ch341a_spi.c
@@ -288,10 +288,10 @@ static uint8_t swap_byte(uint8_t x)
}
/* The assumed map between UIO command bits, pins on CH341A chip and pins on
SPI chip:
- * UIO CH341A SPI CH341A SPI name
+ * UIO CH341A SPI CH341A SPI name Comment
* 0 D0/15 CS/1 (CS0)
- * 1 D1/16 unused (CS1)
- * 2 D2/17 unused (CS2)
+ * 1 D1/16 unused (CS1) nACT, drives low when flashrom
active
+ * 2 D2/17 unused (CS2) ACT, drives high when flashrom
active
* 3 D3/18 SCK/6 (DCK)
* 4 D4/19 unused (DOUT2)
* 5 D5/20 SI/5 (DOUT)
@@ -299,12 +299,15 @@ static uint8_t swap_byte(uint8_t x)
* mapped as follows:
* D6/21 unused (DIN2)
* D7/22 SO/2 (DIN)
+ * CS1 and CS2 are driven nACT & ACT as a bonus by flashrom for ISP uses to
drive a
+ * reset signal or similar. Note that the tristate state is a weak pullup, so
using
+ * CS2 would need an external pull-down.
*/
static int32_t enable_pins(bool enable)
{
uint8_t buf[] = {
CH341A_CMD_UIO_STREAM,
- CH341A_CMD_UIO_STM_OUT | 0x37, // CS high (all of them), SCK=0,
DOUT*=1
+ CH341A_CMD_UIO_STM_OUT | (enable ? 0x35 : 0x33), // SCK=0,
DOUT*=1, CS*= see above
CH341A_CMD_UIO_STM_DIR | (enable ? 0x3F : 0x00), // Interface
output enable / disable
CH341A_CMD_UIO_STM_END,
};
@@ -327,11 +330,11 @@ static void pluck_cs(uint8_t *ptr)
stored_delay_us = 0;
}
*ptr++ = CH341A_CMD_UIO_STREAM;
- *ptr++ = CH341A_CMD_UIO_STM_OUT | 0x37; /* deasserted */
+ *ptr++ = CH341A_CMD_UIO_STM_OUT | 0x35; /* deasserted */
int i;
for (i = 0; i < delay_cnt; i++)
- *ptr++ = CH341A_CMD_UIO_STM_OUT | 0x37; /* "delay" */
- *ptr++ = CH341A_CMD_UIO_STM_OUT | 0x36; /* asserted */
+ *ptr++ = CH341A_CMD_UIO_STM_OUT | 0x35; /* "delay" */
+ *ptr++ = CH341A_CMD_UIO_STM_OUT | 0x34; /* asserted */
*ptr++ = CH341A_CMD_UIO_STM_END;
}
--
2.7.1
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