Re: [PATCH] tty/serial: atmel: ensure state is restored after suspending
From: Nicolas Ferre <hidden>
Date: 2017-02-06 09:31:19
Also in:
linux-arm-kernel, lkml
Le 03/02/2017 à 23:53, Alexandre Belloni a écrit :
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 <redacted>
Reviewed-by: Nicolas Ferre <nicolas.ferre@microchip.com> Thanks,
quoted hunk ↗ jump to hunk
--- 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);
-- Nicolas Ferre