From d4993beec4bcb4f667f2d6120d238a70d07489b4 Mon Sep 17 00:00:00 2001 From: Paul Fertser Date: Wed, 18 Sep 2013 23:42:50 +0400 Subject: [PATCH] bcm2835gpio: use maximum drive strength According to the docs, the default drive strength for the GPIO pads is 8mA but they're capable of 16mA. Configure GPIO 0-27 to use the maximum (as they might be used on high enough frequency with JTAG). Change-Id: I621737a1b0a855bb97b56ce2cc46c0e385b74f5d Signed-off-by: Paul Fertser Reviewed-on: http://openocd.zylin.com/1633 Tested-by: jenkins Reviewed-by: Spencer Oliver --- src/jtag/drivers/bcm2835gpio.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/src/jtag/drivers/bcm2835gpio.c b/src/jtag/drivers/bcm2835gpio.c index 5af92c363..a2ba8e642 100644 --- a/src/jtag/drivers/bcm2835gpio.c +++ b/src/jtag/drivers/bcm2835gpio.c @@ -33,6 +33,9 @@ #define BCM2835_PERI_BASE 0x20000000 #define BCM2835_GPIO_BASE (BCM2835_PERI_BASE + 0x200000) /* GPIO controller */ +#define BCM2835_PADS_GPIO_0_27 (BCM2835_PERI_BASE + 0x100000) +#define BCM2835_PADS_GPIO_0_27_OFFSET (0x2c / 4) + /* GPIO setup macros */ #define MODE_GPIO(g) (*(pio_base+((g)/10))>>(((g)%10)*3) & 7) #define INP_GPIO(g) do { *(pio_base+((g)/10)) &= ~(7<<(((g)%10)*3)); } while (0) @@ -319,6 +322,19 @@ static int bcm2835gpio_init(void) return ERROR_JTAG_INIT_FAILED; } + static volatile uint32_t *pads_base; + pads_base = mmap(NULL, sysconf(_SC_PAGE_SIZE), PROT_READ | PROT_WRITE, + MAP_SHARED, dev_mem_fd, BCM2835_PADS_GPIO_0_27); + + if (pads_base == MAP_FAILED) { + perror("mmap"); + close(dev_mem_fd); + return ERROR_JTAG_INIT_FAILED; + } + + /* set 16mA drive strength */ + pads_base[BCM2835_PADS_GPIO_0_27_OFFSET] = 0x5a000018 + 7; + tdo_gpio_mode = MODE_GPIO(tdo_gpio); tdi_gpio_mode = MODE_GPIO(tdi_gpio); tck_gpio_mode = MODE_GPIO(tck_gpio);