When going to suspend, the UART registers may be lost because the power to
VDDcore is cut. This is not an issue in the normal case but when
no_console_suspend is used, we need to restore the registers in order to
get a functional console.
Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/atmel_serial.c | 44 +++++++++++++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 168b10cad47b..22e0a73c0cb7 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -175,6 +175,17 @@ struct atmel_uart_port {
unsigned int pending_status;
spinlock_t lock_suspended;
+ struct {
+ u32 cr;
+ u32 mr;
+ u32 imr;
+ u32 brgr;
+ u32 rtor;
+ u32 ttgr;
+ u32 fmr;
+ u32 fimr;
+ } cache;
+
int (*prepare_rx)(struct uart_port *port);
int (*prepare_tx)(struct uart_port *port);
void (*schedule_rx)(struct uart_port *port);
@@ -2649,6 +2660,20 @@ static int atmel_serial_suspend(struct platform_device *pdev,
cpu_relax();
}
+ if (atmel_is_console_port(port) && !console_suspend_enabled) {
+ /* Cache register values as we won't get a full shutdown/startup
+ * cycle
+ */
+ atmel_port->cache.mr = atmel_uart_readl(port, ATMEL_US_MR);
+ atmel_port->cache.imr = atmel_uart_readl(port, ATMEL_US_IMR);
+ atmel_port->cache.brgr = atmel_uart_readl(port, ATMEL_US_BRGR);
+ atmel_port->cache.rtor = atmel_uart_readl(port,
+ atmel_port->rtor);
+ atmel_port->cache.ttgr = atmel_uart_readl(port, ATMEL_US_TTGR);
+ atmel_port->cache.fmr = atmel_uart_readl(port, ATMEL_US_FMR);
+ atmel_port->cache.fimr = atmel_uart_readl(port, ATMEL_US_FIMR);
+ }
+
/* we can not wake up if we're running on slow clock */
atmel_port->may_wakeup = device_may_wakeup(&pdev->dev);
if (atmel_serial_clk_will_stop()) {
@@ -2671,6 +2696,25 @@ static int atmel_serial_resume(struct platform_device *pdev)
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
unsigned long flags;
+ if (atmel_is_console_port(port) && !console_suspend_enabled) {
+ atmel_uart_writel(port, ATMEL_US_MR, atmel_port->cache.mr);
+ atmel_uart_writel(port, ATMEL_US_IER, atmel_port->cache.imr);
+ atmel_uart_writel(port, ATMEL_US_BRGR, atmel_port->cache.brgr);
+ atmel_uart_writel(port, atmel_port->rtor,
+ atmel_port->cache.rtor);
+ atmel_uart_writel(port, ATMEL_US_TTGR, atmel_port->cache.ttgr);
+
+ if (atmel_port->fifo_size) {
+ atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_FIFOEN |
+ ATMEL_US_RXFCLR | ATMEL_US_TXFLCLR);
+ atmel_uart_writel(port, ATMEL_US_FMR,
+ atmel_port->cache.fmr);
+ atmel_uart_writel(port, ATMEL_US_FIER,
+ atmel_port->cache.fimr);
+ }
+ atmel_start_rx(port);
+ }
+
spin_lock_irqsave(&atmel_port->lock_suspended, flags);
if (atmel_port->pending) {
atmel_handle_receive(port, atmel_port->pending);
--
2.11.0
--
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