programmer: Add bitbanging programmer driver for Linux libgpiod
With this driver, any single board computer, old smartphone, etc. with
a few spare GPIOs can be used for flashrom.
Tested by reading of a 2048 kB flash chip on a Qualcomm MSM8916 SoC
@800 MHz, ran the following command:
time flashrom -p linux_gpiod:gpiochip=0,cs=18,sck=19,mosi=13,miso=56 -r test.bin
This command uses /dev/gpiochip0 with the specified GPIO numbers for the
SPI lines. All arguments are mandatory.
Output:
[...]
Found GigaDevice flash chip "GD25LQ16" (2048 kB, SPI) on linux_gpiod.
[...]
real 1m 33.96s
Change-Id: Icad3eb7764f28feaea51bda3a7893da724c86d06
Signed-off-by: Steve Markgraf <steve@steve-m.de>
Signed-off-by: Nico Huber <nico.h@gmx.de>
diff --git a/flashrom.8.tmpl b/flashrom.8.tmpl
index db2edb1..9ef8928 100644
--- a/flashrom.8.tmpl
+++ b/flashrom.8.tmpl
@@ -331,6 +331,8 @@
.sp
.BR "* ogp_spi" " (for SPI flash ROMs on Open Graphics Project graphics card)"
.sp
+.BR "* linux_gpio_spi" " (for SPI flash ROMs attached to a GPIO chip device accessible via /dev/gpiochipX on Linux)"
+.sp
.BR "* linux_mtd" " (for SPI flash ROMs accessible via /dev/mtdX on Linux)"
.sp
.BR "* linux_spi" " (for SPI flash ROMs accessible via /dev/spidevX.Y on Linux)"
@@ -1132,6 +1134,34 @@
.B nic3com et al.\&
section above.
.SS
+.BR "linux_gpio_spi " programmer
+.IP
+Either the GPIO device node or the chip number as well as the GPIO numbers
+of the SPI lines must be specified like in the following examples:
+.sp
+.B " flashrom \-p linux_gpio_spi:dev=/dev/gpiochip0,cs=8,sck=11,mosi=10,miso=9"
+.sp
+or
+.sp
+.B " flashrom \-p linux_gpio_spi:gpiochip=0,cs=8,sck=11,mosi=10,miso=9"
+.sp
+Here,
+.B gpiochip=0
+selects the GPIO chip 0, accessible through Linux device node /dev/gpiochip0, and the
+.B cs, sck, mosi, miso
+arguments select the GPIO numbers used as SPI lines connected to the flash ROM chip. In this example
+the GPIO numbers of the hardware SPI lines of of a Raspberry Pi single board computer are specified.
+All programmer arguments are mandatory.
+Note that this is a bitbanged driver, and if your device has a hardware SPI controller, use the
+.B linux_spi
+programmer driver instead for better performance.
+.sp
+Refer to the output of the
+.B gpioinfo
+utility to make sure the GPIO numbers are correct and unused.
+.sp
+Please note that the linux_gpio_spi driver only works on Linux, and depends on libgpiod.
+.SS
.BR "linux_mtd " programmer
.IP
You may specify the MTD device to use with the
@@ -1584,6 +1614,8 @@
.br
Stephan Guilloux
.br
+Steve Markgraf
+.br
Steven James
.br
Urja Rannikko