[PATCH v4 24/28] board: google: Add board_debug_uart_init() for Trogdor

[Casey Connolly]

On 5/24/25 00:58, Stephen Boyd wrote:
> Implement board_debug_uart_init() for Trogdor boards so that the debug
> UART can be used. Initialize the clk to XO speed (19.2MHz) and change
> the pin configuration to mux out the uart hardware on the pins that are
> connected to the closed case debug (CCD) port for the AP. This is enough
> to get the early debug console working on boards like Lazor, but it
> should work for all Google Trogdor boards.
> 
> Signed-off-by: Stephen Boyd <swboyd at chromium.org>

Reviewed-by: Casey Connolly <casey.connolly at linaro.org>

Would you be willing to add a MAINTAINERS file here for the trogdor 
specific bits?

Kind regards,> ---
>   board/google/trogdor/Makefile     |  3 +++
>   board/google/trogdor/debug.config |  6 +++++
>   board/google/trogdor/debug_uart.c | 41 +++++++++++++++++++++++++++++++
>   3 files changed, 50 insertions(+)
>   create mode 100644 board/google/trogdor/Makefile
>   create mode 100644 board/google/trogdor/debug.config
>   create mode 100644 board/google/trogdor/debug_uart.c
> 
> diff --git a/board/google/trogdor/Makefile b/board/google/trogdor/Makefile
> new file mode 100644
> index 000000000000..fd2933cf1e6f
> --- /dev/null
> +++ b/board/google/trogdor/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +obj-$(CONFIG_DEBUG_UART_BOARD_INIT) += debug_uart.o
> diff --git a/board/google/trogdor/debug.config b/board/google/trogdor/debug.config
> new file mode 100644
> index 000000000000..7d8a6706a92e
> --- /dev/null
> +++ b/board/google/trogdor/debug.config
> @@ -0,0 +1,6 @@
> +CONFIG_DEBUG_UART=y
> +CONFIG_DEBUG_UART_ANNOUNCE=y
> +CONFIG_DEBUG_UART_BASE=0xa88000
> +CONFIG_DEBUG_UART_MSM_GENI=y
> +CONFIG_DEBUG_UART_CLOCK=36864000
> +CONFIG_DEBUG_UART_BOARD_INIT=y
> diff --git a/board/google/trogdor/debug_uart.c b/board/google/trogdor/debug_uart.c
> new file mode 100644
> index 000000000000..3d15d0d77728
> --- /dev/null
> +++ b/board/google/trogdor/debug_uart.c
> @@ -0,0 +1,41 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <asm/io.h>
> +#include <debug_uart.h>
> +#include <linux/delay.h>
> +
> +/*
> + * Enable the UART8 clks and pinctrl settings for SC7180.
> + *
> + * The debug UART goes out over CCD. The debug uart clk setting is 36864000 to
> + * make the buad rate calculation come out properly for the qcom geni serial
> + * driver.
> + */
> +void board_debug_uart_init(void)
> +{
> +	u32 val, mask;
> +	unsigned int timeout = 100;
> +
> +	/* Enable wrap1_s2 clk */
> +	val = readl(0x100000 + 0x52008);
> +	val |= BIT(24);
> +	writel(val, 0x100000 + 0x52008);
> +	/* Wait for enable */
> +	do {
> +		val = readl(0x100000 + 0x18274);
> +		mask = GENMASK(30, 28) | BIT(31);
> +		val &= mask;
> +		if ((val & BIT(31)) == 0 || ((val >> 28) & 7) == 1)
> +			break;
> +		udelay(10);
> +	} while (timeout--);
> +
> +	/*
> +	 * Configure GPIOs
> +	 * Bits: 0-1 = pull
> +	 * Bits: 2-4 = func
> +	 * Bits: 6-8 = drive strength
> +	 */
> +	writel(0x3 | (1 << 2), 0x3900000 + (0x1000 * 44)); // Pin 44 - PULL_UP, func1 (qup12), 2ma
> +	writel(0x3 | (1 << 2), 0x3900000 + (0x1000 * 45)); // Pin 45 - PULL_UP, func1 (qup12), 2ma
> +}

-- 
Casey (she/they)