Introduce support for early debugging. This relies on the previous stage
bootloader to initialise the UART clocks, when running with U-Boot as
the primary bootloader this feature doesn't work. It will require a way
to configure the clocks before the driver model is available.
Signed-off-by: Caleb Connolly <caleb.conno...@linaro.org>
---
drivers/serial/Kconfig | 8 ++++++++
drivers/serial/serial_msm.c | 32 ++++++++++++++++++++++++++++++++
2 files changed, 40 insertions(+)
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 26460c4e0cab..fbd351a47859 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -319,6 +319,14 @@ config DEBUG_UART_S5P
will need to provide parameters to make this work. The driver will
be available until the real driver-model serial is running.
+config DEBUG_UART_MSM
+ bool "Qualcomm QUP UART debug"
+ depends on ARCH_SNAPDRAGON
+ help
+ Select this to enable a debug UART using the serial_msm driver. You
+ will need to provide parameters to make this work. The driver will
+ be available until the real driver-model serial is running.
+
config DEBUG_UART_MSM_GENI
bool "Qualcomm snapdragon"
depends on ARCH_SNAPDRAGON
diff --git a/drivers/serial/serial_msm.c b/drivers/serial/serial_msm.c
index a22623c316ed..19a5a3a788f7 100644
--- a/drivers/serial/serial_msm.c
+++ b/drivers/serial/serial_msm.c
@@ -253,3 +253,35 @@ U_BOOT_DRIVER(serial_msm) = {
.probe = msm_serial_probe,
.ops = &msm_serial_ops,
};
+
+#ifdef CONFIG_DEBUG_UART_MSM
+
+static struct msm_serial_data init_serial_data = {
+ .base = CONFIG_VAL(DEBUG_UART_BASE),
+ .clk_bit_rate = UART_DM_CLK_RX_TX_BIT_RATE,
+};
+
+#include <debug_uart.h>
+
+static inline void _debug_uart_init(void)
+{
+ uart_dm_init(&init_serial_data);
+}
+
+static inline void _debug_uart_putc(int ch)
+{
+ struct msm_serial_data *priv = &init_serial_data;
+
+ while (!(readl(priv->base + UARTDM_SR) & UARTDM_SR_TX_EMPTY) &&
+ !(readl(priv->base + UARTDM_ISR) & UARTDM_ISR_TX_READY))
+ ;
+
+ writel(UARTDM_CR_CMD_RESET_TX_READY, priv->base + UARTDM_CR);
+
+ writel(1, priv->base + UARTDM_NCF_TX);
+ writel(ch, priv->base + UARTDM_TF);
+}
+
+DEBUG_UART_FUNCS
+
+#endif
--
2.43.0
