Messages in this thread Patch in this message | | | From | Eduardo Valentin <> | Subject | [PATCH 5/8] serial: imx: save and restore context in the suspend path | Date | Sun, 9 Aug 2015 11:19:06 -0700 |
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This change teaches the imx serial driver to save its context and restore it across suspend and resume path. To do so, it introduces serial_imx_restore_context() and serial_imx_save_context() functions. They use a shadow set of registers to save key registers and restore them accordingly. These functions can be reused on other situations, when the device context is lost.
Cc: Fabio Stevam <festevam@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jslaby@suse.com> Cc: linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Eduardo Valentin <edubezval@gmail.com> --- drivers/tty/serial/imx.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index a03855d..494b182 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -217,6 +217,8 @@ struct imx_port { unsigned int tx_bytes; unsigned int dma_tx_nents; wait_queue_head_t dma_wait; + unsigned int saved_reg[8]; + bool context_saved; }; struct imx_port_ucrs { @@ -1803,6 +1805,36 @@ static struct uart_driver imx_reg = { .cons = IMX_CONSOLE, }; +static void serial_imx_restore_context(struct imx_port *sport) +{ + if (!sport->context_saved) + return; + + writel(sport->saved_reg[4], sport->port.membase + UFCR); + writel(sport->saved_reg[5], sport->port.membase + UBIR); + writel(sport->saved_reg[6], sport->port.membase + UBMR); + writel(sport->saved_reg[7], sport->port.membase + IMX21_UTS); + writel(sport->saved_reg[0], sport->port.membase + UCR1); + writel(sport->saved_reg[1] | 0x1, sport->port.membase + UCR2); + writel(sport->saved_reg[2], sport->port.membase + UCR3); + writel(sport->saved_reg[3], sport->port.membase + UCR4); + sport->context_saved = false; +} + +static void serial_imx_save_context(struct imx_port *sport) +{ + /* Save necessary regs */ + sport->saved_reg[0] = readl(sport->port.membase + UCR1); + sport->saved_reg[1] = readl(sport->port.membase + UCR2); + sport->saved_reg[2] = readl(sport->port.membase + UCR3); + sport->saved_reg[3] = readl(sport->port.membase + UCR4); + sport->saved_reg[4] = readl(sport->port.membase + UFCR); + sport->saved_reg[5] = readl(sport->port.membase + UBIR); + sport->saved_reg[6] = readl(sport->port.membase + UBMR); + sport->saved_reg[7] = readl(sport->port.membase + IMX21_UTS); + sport->context_saved = true; +} + static void serial_imx_enable_wakeup(struct imx_port *sport, bool on) { unsigned int val; @@ -1826,6 +1858,7 @@ static int serial_imx_suspend(struct device *dev) { struct imx_port *sport = dev_get_drvdata(dev); + serial_imx_save_context(sport); /* enable wakeup from i.MX UART */ serial_imx_enable_wakeup(sport, true); @@ -1841,6 +1874,7 @@ static int serial_imx_resume(struct device *dev) /* disable wakeup from i.MX UART */ serial_imx_enable_wakeup(sport, false); + serial_imx_restore_context(sport); uart_resume_port(&imx_reg, &sport->port); return 0; -- 2.5.0
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