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tty/serial: atmel: ensure state is restored after suspending

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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@free-electrons.com>
Reviewed-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexandre Belloni 2017-02-03 23:53:16 +01:00 committed by Greg Kroah-Hartman
parent 424d79183a
commit 6a5f0e2f93
1 changed files with 44 additions and 0 deletions
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44
drivers/tty/serial/atmel_serial.c
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@ -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);
@ -2659,6 +2670,20 @@ 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()) {
@ -2681,6 +2706,25 @@ 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);