Now that we have all infrastructure in place to dynamically determine whether a serial device is actually usable (read: routed to user accessible pins), we can wire it up to the board.
This patch adds support to determine whether the pl011 or mini-uart or no serial is routed to the UART RX/TX pins on the Raspberry Pi family of boards.
Signed-off-by: Alexander Graf agraf@suse.de --- board/raspberrypi/rpi/rpi.c | 69 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+)
diff --git a/board/raspberrypi/rpi/rpi.c b/board/raspberrypi/rpi/rpi.c index a96d5d8952..b0cdad70f7 100644 --- a/board/raspberrypi/rpi/rpi.c +++ b/board/raspberrypi/rpi/rpi.c @@ -24,9 +24,16 @@ #include <asm/armv8/mmu.h> #endif #include <watchdog.h> +#include <asm/io.h>
DECLARE_GLOBAL_DATA_PTR;
+/* + * This is the GPIO pin that the user facing UART RX line is attached to. + * We use this pin to determine which serial device is available. + */ +#define BCM2835_GPIO_RX 15 + /* From lowlevel_init.S */ extern unsigned long fw_dtb_pointer;
@@ -419,6 +426,68 @@ static void get_board_rev(void) printf("RPI %s (0x%x)\n", model->name, revision); }
+/* + * We may get called before the device model is initialized, so we can not + * rely on the GPIO driver. + */ +int get_func_id(unsigned gpio) +{ + u32 val; + u32 node; + u32 *gpfsel; + fdt_addr_t addr; + fdt_size_t size; + + node = fdt_node_offset_by_compatible(gd->fdt_blob, -1, "brcm,bcm2835-gpio"); + if (node < 0) + return -EINVAL; + + addr = fdtdec_get_addr_size_auto_noparent(gd->fdt_blob, node, "reg", + 0, &size, true); + gpfsel = (void*)addr; + + val = readl(&gpfsel[BCM2835_GPIO_FSEL_BANK(gpio)]); + + return (val >> BCM2835_GPIO_FSEL_SHIFT(gpio) & BCM2835_GPIO_FSEL_MASK); +} + + +/* + * The RPi has 2 serial ports: A PL011 based one and the mini-uart. + * Depending on firmware configuration, either can be configured to either + * nothing, the wifi adapter or serial output. + * + * We only want to use the serial port that is user facing to not + * end up with a potentially unresponsive serial port. Due to this + * we need to check whether the serial device is actually connected + * to the UART RX/TX pins on the RPi GPIO pin bar. + * + * We only allow U-Boot to instantiate the serial driver for the serial + * device that is muxed correctly. + */ +int board_check_serial(struct udevice *dev) +{ + int func; + + printf("Checking serial %s\n", dev->name); + + if (device_is_compatible(dev, "arm,pl011")) { + func = BCM2835_GPIO_ALT0; + } else if (device_is_compatible(dev, "brcm,bcm2835-aux-uart")) { + func = BCM2835_GPIO_ALT5; + } else { + return 0; + } + + if (get_func_id(BCM2835_GPIO_RX) != func) { + printf("Disabling serial %s\n", dev->name); + return -ENODEV; + } + + printf("Enabling serial %s\n", dev->name); + return 0; +} + int board_init(void) { #ifdef CONFIG_HW_WATCHDOG