From 25a5bceb930b6db3f29b1af58133ebbd8ea5f85c Mon Sep 17 00:00:00 2001
From: Alan Green <avg@google.com>
Date: Fri, 8 Jan 2021 09:36:45 +1100
Subject: ft2232_spi.c: release I/Os on shutdown
Reset FTDI I/O pins to high-Z (input) when shutting down. This allows
other devices to use the SPI bus without having to disconnect the
programmer.
This change will introduce a backward incompatibility in the case where
a user is relying on the state of FTDI outputs post-programming (eg. to
disallow another device from driving CS low).
However, there are likely more cases where releasing the SPI bus is the
correct thing to do.
Signed-off-by: Alan Green <avg@google.com>
Change-Id: I9fae55e532595752983f55fac2298f81699dbe5b
Reviewed-on: https://review.coreboot.org/c/flashrom/+/49632
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
---
ft2232_spi.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/ft2232_spi.c b/ft2232_spi.c
index 65ff4490..c963a45b 100644
--- a/ft2232_spi.c
+++ b/ft2232_spi.c
@@ -159,6 +159,30 @@ static int get_buf(struct ftdi_context *ftdic, const unsigned char *buf,
return 0;
}
+static int ft2232_shutdown(void *data)
+{
+ int f;
+ struct ftdi_context *ftdic = (struct ftdi_context *) data;
+ unsigned char buf[3];
+
+ msg_pdbg("Releasing I/Os\n");
+ buf[0] = SET_BITS_LOW;
+ buf[1] = 0; /* Output byte ignored */
+ buf[2] = 0; /* Pin direction: all inputs */
+ if (send_buf(ftdic, buf, 3)) {
+ msg_perr("Unable to set pins back inputs: (%s)\n",
+ ftdi_get_error_string(ftdic));
+ }
+
+ if ((f = ftdi_usb_close(ftdic)) < 0) {
+ msg_perr("Unable to close FTDI device: %d (%s)\n", f,
+ ftdi_get_error_string(ftdic));
+ return f;
+ }
+
+ return 0;
+}
+
static int ft2232_spi_send_command(const struct flashctx *flash,
unsigned int writecnt, unsigned int readcnt,
const unsigned char *writearr,
@@ -453,6 +477,7 @@ int ft2232_spi_init(void)
goto ftdi_err;
}
+ register_shutdown(ft2232_shutdown, ftdic);
register_spi_master(&spi_master_ft2232);
return 0;
--
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