Add support for Waveshare 2CH RS232 daughter board

Signed-off-by: Marc Zyngier <maz@kernel.org>

2 files changed, 59 insertions, 1 deletions

diff --git a/m1-pd-bmc.h b/m1-pd-bmc.h
index edad800..83abc9c 100644
--- a/m1-pd-bmc.h
+++ b/m1-pd-bmc.h
@@ -29,7 +29,9 @@ enum m1_pd_bmc_pins {
 	UART_RX,
 	SBU_SWAP,
 	SEL_USB,
-	M1_BMC_PIN_END = SEL_USB,
+	LED_R_TX,
+	LED_R_RX,
+	M1_BMC_PIN_END = LED_R_RX,
 };
 
 struct hw_context {
diff --git a/start.c b/start.c
index f3b940c..d8d9dd5 100644
--- a/start.c
+++ b/start.c
@@ -54,6 +54,25 @@ static const struct gpio_pin_config m1_pd_bmc_pin_config0[] = {
 	},
 };
 
+static const struct gpio_pin_config waveshare_2ch_rs232_config0[] = {
+	[M1_BMC_PIN_START ... M1_BMC_PIN_END] = {
+		.skip	= true,
+	},
+	/* Prevent the unused leds from drawing much curent */
+	[LED_R_TX] = {
+		.pin	= 0,
+		.mode	= GPIO_FUNC_SIO,
+		.dir	= GPIO_IN,
+		.pu	= true,
+	},
+	[LED_R_RX] = {
+		.pin	= 1,
+		.mode	= GPIO_FUNC_SIO,
+		.dir	= GPIO_IN,
+		.pu	= true,
+	},
+};
+
 static const struct gpio_pin_config m1_pd_bmc_pin_config1[] = {
 	[M1_BMC_PIN_START ... M1_BMC_PIN_END] = {
 		.skip	= true,
@@ -102,6 +121,20 @@ static const struct gpio_pin_config m1_pd_bmc_pin_config1[] = {
 	},
 };
 
+static const struct gpio_pin_config waveshare_2ch_rs232_config1[] = {
+	[M1_BMC_PIN_START ... M1_BMC_PIN_END] = {
+		.skip	= true,
+	},
+	[UART_TX] = {		/* UART1 */
+		.pin	= 4,
+		.mode	= GPIO_FUNC_UART,
+	},
+	[UART_RX] = {		/* UART1 */
+		.pin	= 5,
+		.mode	= GPIO_FUNC_UART,
+	},
+};
+
 static struct {
 	/*
 	 * we rely on prod/cons rollover behaviour, and buf must cover
@@ -205,6 +238,26 @@ static void m1_pd_bmc_system_init(const struct hw_context *hw)
 		m1_pd_bmc_gpio_setup_one(&hw->pins[i]);
 }
 
+static bool apply_waveshare_2ch_rs232_overrides(void)
+{
+	/*
+	 * Hack: check for PUPs on 0/1, and assumes this is a dual
+	 * RS232 board plugged in. Ideally, we'd also check UART1 on
+	 * 4/5, but this looks unreliable. If this gets in the way,
+	 * turn it into a compilation option instead.
+	 */
+	if (!(gpio_get(waveshare_2ch_rs232_config0[LED_R_TX].pin) &&
+	      gpio_get(waveshare_2ch_rs232_config0[LED_R_RX].pin)))
+		return false;
+
+	for (int i = 0; i < ARRAY_SIZE(waveshare_2ch_rs232_config0); i++)
+		m1_pd_bmc_gpio_setup_one(&waveshare_2ch_rs232_config0[i]);
+	for (int i = 0; i < ARRAY_SIZE(waveshare_2ch_rs232_config1); i++)
+		m1_pd_bmc_gpio_setup_one(&waveshare_2ch_rs232_config1[i]);
+
+	return true;
+}
+
 static void usb_tx_bytes(int32_t port, const char *ptr, int len)
 {
         if (!tud_cdc_n_connected(port))
@@ -353,6 +406,9 @@ int main(void)
 	if (!success)
 		__printf(port, "WARNING: Nominal frequency NOT reached\n");
 
+	if (apply_waveshare_2ch_rs232_overrides())
+		__printf(port, "Detected Waveshare 2CH RS232, switching UART1\n");
+
 	m1_pd_bmc_fusb_setup(0, &hw0);
 	m1_pd_bmc_fusb_setup(1, &hw1);