[PATCH 16/20] serial: stm32: fix fifo usage

[Bich HEMON]

From: Bich Hemon <bich.hemon at st.com>

Fifo is available starting with stm32h7. Add has_fifo flag to use fifo
only when possible.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier at st.com>
---
 drivers/tty/serial/stm32-usart.c | 9 ++++++++-
 drivers/tty/serial/stm32-usart.h | 2 ++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 05d89b0..d241056 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -49,6 +49,10 @@ static void stm32_serial_debugfs(struct stm32_port *stm32port,
 {
 	struct device *dev = stm32port->port.dev;
 
+	/* For now, debugfs is only used for fifo, then skip if unsupported */
+	if (!stm32port->info->cfg.has_fifo)
+		return;
+
 	if (!stm32_debugfs_root)
 		stm32_debugfs_root = debugfs_create_dir("usart-stm32", NULL);
 
@@ -63,6 +67,9 @@ static void stm32_serial_debugfs(struct stm32_port *stm32port,
 
 static void stm32_serial_debugfs_rm(struct stm32_port *stm32port)
 {
+	if (!stm32port->info->cfg.has_fifo)
+		return;
+
 	debugfs_remove_recursive(stm32port->debugfs_dir);
 	if (atomic_dec_and_test(&stm32_debugfs_cnt)) {
 		debugfs_remove_recursive(stm32_debugfs_root);
@@ -775,6 +782,7 @@ static int stm32_init_port(struct stm32_port *stm32port,
 	port->dev	= &pdev->dev;
 	port->irq	= platform_get_irq(pdev, 0);
 	stm32port->wakeirq = platform_get_irq(pdev, 1);
+	stm32port->fifoen = stm32port->info->cfg.has_fifo;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	port->membase = devm_ioremap_resource(&pdev->dev, res);
@@ -824,7 +832,6 @@ static struct stm32_port *stm32_of_get_stm32_port(struct platform_device *pdev)
 	stm32_ports[id].hw_flow_control = of_property_read_bool(np,
 							"st,hw-flow-ctrl");
 	stm32_ports[id].port.line = id;
-	stm32_ports[id].fifoen = true;
 	stm32_ports[id].rx_irq = USART_CR1_RXNEIE;
 	stm32_ports[id].last_res = RX_BUF_L;
 	return &stm32_ports[id];
diff --git a/drivers/tty/serial/stm32-usart.h b/drivers/tty/serial/stm32-usart.h
index 98dbf38..25ed28b 100644
--- a/drivers/tty/serial/stm32-usart.h
+++ b/drivers/tty/serial/stm32-usart.h
@@ -25,6 +25,7 @@ struct stm32_usart_config {
 	u8 uart_enable_bit; /* USART_CR1_UE */
 	bool has_7bits_data;
 	bool has_wakeup;
+	bool has_fifo;
 };
 
 struct stm32_usart_info {
@@ -93,6 +94,7 @@ struct stm32_usart_info stm32h7_info = {
 		.uart_enable_bit = 0,
 		.has_7bits_data = true,
 		.has_wakeup = true,
+		.has_fifo = true,
 	}
 };
 
-- 
1.9.1