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

[Casey Connolly]

On 5/28/25 13:25, Caleb Connolly via groups.io wrote:


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 <swb...@chromium.org>

Reviewed-by: Casey Connolly <casey.conno...@linaro.org>

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

Oh right, CI fails since the trogdor defconfig doesn't have a 
maintainer, I'm happy to put it under ARM SNAPDRAGON but it would be 
great if you're willing to take it up. Please let me know ASAP (feel 
free to send a patch adding board/google/trogdor/MAINTAINERS on top of 
this series) so I can pick this up :)

Kind regards,>
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)