Re: [PATCH 5/7] Serial: OMAP: add runtime pm support for omap-serial driver

[Kevin Hilman <khilman@ti.com>]

"Govindraj.R" <govindraj.raja@ti.com> writes:

> Adapts omap-serial driver to use pm_runtime api's.
>
> 1.) Populate reg values to uart port which can be used for context restore.
> 2.) Moved Erratum handling func to driver from serial.c
> 3.) adding port_enable/disable func to enable/disable given uart port.
> 4.) using prepare/resume api's to cut and enable back uart func_clks.
> 5.) using timer to set flag to cut uart clocks based on this flag in
>     sram_idle path.

At least the errata handling should be in a separate patch as it's not
related to runtime PM.

Also, please be sure to test building this driver as a module.  Because
of direct access to hwmod in this patch, it will currently build as a module.

> Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
> ---
>  drivers/tty/serial/omap-serial.c |  304 +++++++++++++++++++++++++++++++++++---
>  1 files changed, 283 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
> index d40924a..bc877b9 100644
> --- a/drivers/tty/serial/omap-serial.c
> +++ b/drivers/tty/serial/omap-serial.c
> @@ -33,10 +33,21 @@
>  #include <linux/clk.h>
>  #include <linux/serial_core.h>
>  #include <linux/irq.h>
> +#include <linux/pm_runtime.h>
>  
>  #include <plat/dma.h>
>  #include <plat/dmtimer.h>
>  #include <plat/omap-serial.h>
> +#include <plat/serial.h>
> +#include <plat/omap_device.h>
> +
> +#ifdef CONFIG_SERIAL_OMAP_CONSOLE
> +#define omap_uart_console(port) ((port)->cons && (port)->cons->index == (port)->line)
> +#else
> +#define omap_uart_console(port)	NULL
> +#endif
> +
> +#define OMAP_UART_CLK_PUT_DELAY (5 * HZ)
>  
>  static struct uart_omap_port *ui[OMAP_MAX_HSUART_PORTS];
>  
> @@ -44,6 +55,7 @@ static struct uart_omap_port *ui[OMAP_MAX_HSUART_PORTS];
>  static void uart_tx_dma_callback(int lch, u16 ch_status, void *data);
>  static void serial_omap_rx_timeout(unsigned long uart_no);
>  static int serial_omap_start_rxdma(struct uart_omap_port *up);
> +static void omap_uart_mdr1_errataset(struct uart_omap_port *up);
>  
>  static inline unsigned int serial_in(struct uart_omap_port *up, int offset)
>  {
> @@ -90,6 +102,73 @@ serial_omap_get_divisor(struct uart_port *port, unsigned int baud)
>  	return port->uartclk/(baud * divisor);
>  }
>  
> +static void omap_uart_smart_idle(struct uart_omap_port *up)
> +{
> +	struct platform_device *pdev = up->pdev;
> +	struct omap_device *od = container_of(pdev, struct omap_device, pdev);
> +
> +	omap_hwmod_set_slave_idlemode(od->hwmods[0], HWMOD_IDLEMODE_SMART);
> +}
> +
> +static void serial_omap_port_disable(struct uart_omap_port *up)
> +{
> +	if (!pm_runtime_suspended(&up->pdev->dev)) {
> +		del_timer(&up->inactivity_timer);
> +		if (omap_uart_console(&up->port))
> +			console_stop(up->port.cons);
> +
> +		pm_runtime_put_sync(&up->pdev->dev);
> +	}
> +}

This function should not be needed.

The timer should be replaced by the auto-suspend feature of runtime PM.

Instead of calling omap_port_disable() callers should call
pm_runtime_put_autosuspend(), and the console_stop() should be part of
the ->runtime_suspend() callback.

Also, why do you check for pm_runtime_suspended()?  Just call it for
every time and we get runtime PM use-counting and statistics for free
and the ->runtime_suspend() callback will be called when the usecount
goes to zero.

> +static void serial_omap_inactivity_timer(unsigned long uart_no)
> +{
> +	struct uart_omap_port *up = ui[uart_no];
> +
> +	up->can_sleep = 1;
> +	omap_uart_smart_idle(up);
> +}

This will not be needed if using the autosuspend feature.

> +static void serial_omap_port_enable(struct uart_omap_port *up)
> +{
> +	if (pm_runtime_suspended(&up->pdev->dev)) {
> +		if (omap_uart_console(&up->port))
> +			console_start(up->port.cons);
> +
> +		pm_runtime_get_sync(&up->pdev->dev);
> +	}
> +
> +	up->can_sleep = 0;
> +	mod_timer(&up->inactivity_timer, jiffies + OMAP_UART_CLK_PUT_DELAY);
> +}

Similarily to the disable side, callers of this function should call
pm_runtime_get_sync() and the console_start() should be in the
->runtime_resume method.

Again, no need to check pm_runtime_suspended() since the runtime PM core
does usecounting already.

> +void omap_uart_prepare_idle(int num)
> +{
> +	struct uart_omap_port *up = ui[num];
> +
> +	if (up && up->can_sleep)
> +		serial_omap_port_disable(up);

		pm_runtime_put_autosuspend()

> +}
> +
> +void omap_uart_resume_idle(int num)
> +{
> +	struct uart_omap_port *up = ui[num];
> +	struct omap_device *od;
> +	struct platform_device *pdev;
> +
> +	if (!up)
> +		return;
> +
> +	pdev = up->pdev;
> +	od = container_of(pdev, struct omap_device, pdev);

	od = to_omap_device(pdev);

> +	if (omap_hmwod_pad_wakeup_status(od->hwmods[0]) == true)
> +		serial_omap_port_enable(up);
> +
> +	if (up->wk_st && (__raw_readl(up->wk_st) & up->wk_mask))
> +		serial_omap_port_enable(up);
> +}

c.f. comments from PATCH 2/7

Also, direct hwmod access and PRCM accesses do not belong in drivers.

Until it is understood why wakeups are not working, these hacks should
stay in mach-omap2/serial.c

>  static void serial_omap_stop_rxdma(struct uart_omap_port *up)
>  {
>  	if (up->uart_dma.rx_dma_used) {
> @@ -105,6 +184,7 @@ static void serial_omap_enable_ms(struct uart_port *port)
>  {
>  	struct uart_omap_port *up = (struct uart_omap_port *)port;
>  
> +	serial_omap_port_enable(up);

	pm_runtime_put_autosuspend()

similarily for all calls to omap_port_enable()

>  	dev_dbg(up->port.dev, "serial_omap_enable_ms+%d\n", up->pdev->id);
>  	up->ier |= UART_IER_MSI;
>  	serial_out(up, UART_IER, up->ier);
> @@ -114,6 +194,7 @@ static void serial_omap_stop_tx(struct uart_port *port)
>  {
>  	struct uart_omap_port *up = (struct uart_omap_port *)port;
>  
> +	serial_omap_port_enable(up);
>  	if (up->use_dma &&
>  		up->uart_dma.tx_dma_channel != OMAP_UART_DMA_CH_FREE) {
>  		/*
> @@ -137,6 +218,7 @@ static void serial_omap_stop_rx(struct uart_port *port)
>  {
>  	struct uart_omap_port *up = (struct uart_omap_port *)port;
>  
> +	serial_omap_port_enable(up);
>  	if (up->use_dma)
>  		serial_omap_stop_rxdma(up);
>  	up->ier &= ~UART_IER_RLSI;
> @@ -258,6 +340,7 @@ static void serial_omap_start_tx(struct uart_port *port)
>  	unsigned int start;
>  	int ret = 0;
>  
> +	serial_omap_port_enable(up);
>  	if (!up->use_dma) {
>  		serial_omap_enable_ier_thri(up);
>  		return;
> @@ -351,6 +434,7 @@ static inline irqreturn_t serial_omap_irq(int irq, void *dev_id)
>  	unsigned int iir, lsr;
>  	unsigned long flags;
>  
> +	serial_omap_port_enable(up);
>  	iir = serial_in(up, UART_IIR);
>  	if (iir & UART_IIR_NO_INT)
>  		return IRQ_NONE;
> @@ -385,6 +469,7 @@ static unsigned int serial_omap_tx_empty(struct uart_port *port)
>  	unsigned long flags = 0;
>  	unsigned int ret = 0;
>  
> +	serial_omap_port_enable(up);
>  	dev_dbg(up->port.dev, "serial_omap_tx_empty+%d\n", up->pdev->id);
>  	spin_lock_irqsave(&up->port.lock, flags);
>  	ret = serial_in(up, UART_LSR) & UART_LSR_TEMT ? TIOCSER_TEMT : 0;
> @@ -399,6 +484,7 @@ static unsigned int serial_omap_get_mctrl(struct uart_port *port)
>  	unsigned char status;
>  	unsigned int ret = 0;
>  
> +	serial_omap_port_enable(up);
>  	status = check_modem_status(up);
>  	dev_dbg(up->port.dev, "serial_omap_get_mctrl+%d\n", up->pdev->id);
>  
> @@ -419,6 +505,7 @@ static void serial_omap_set_mctrl(struct uart_port *port, unsigned int mctrl)
>  	unsigned char mcr = 0;
>  
>  	dev_dbg(up->port.dev, "serial_omap_set_mctrl+%d\n", up->pdev->id);
> +	serial_omap_port_enable(up);
>  	if (mctrl & TIOCM_RTS)
>  		mcr |= UART_MCR_RTS;
>  	if (mctrl & TIOCM_DTR)
> @@ -440,6 +527,7 @@ static void serial_omap_break_ctl(struct uart_port *port, int break_state)
>  	unsigned long flags = 0;
>  
>  	dev_dbg(up->port.dev, "serial_omap_break_ctl+%d\n", up->pdev->id);
> +	serial_omap_port_enable(up);
>  	spin_lock_irqsave(&up->port.lock, flags);
>  	if (break_state == -1)
>  		up->lcr |= UART_LCR_SBC;
> @@ -465,6 +553,7 @@ static int serial_omap_startup(struct uart_port *port)
>  
>  	dev_dbg(up->port.dev, "serial_omap_startup+%d\n", up->pdev->id);
>  
> +	serial_omap_port_enable(up);
>  	/*
>  	 * Clear the FIFO buffers and disable them.
>  	 * (they will be reenabled in set_termios())
> @@ -530,6 +619,8 @@ static void serial_omap_shutdown(struct uart_port *port)
>  	unsigned long flags = 0;
>  
>  	dev_dbg(up->port.dev, "serial_omap_shutdown+%d\n", up->pdev->id);
> +
> +	serial_omap_port_enable(up);
>  	/*
>  	 * Disable interrupts from this port
>  	 */
> @@ -668,6 +759,10 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
>  	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/13);
>  	quot = serial_omap_get_divisor(port, baud);
>  
> +	up->dll = quot & 0xff;
> +	up->dlh = quot >> 8;
> +	up->mdr1 = UART_OMAP_MDR1_DISABLE;
> +
>  	up->fcr = UART_FCR_R_TRIG_01 | UART_FCR_T_TRIG_01 |
>  			UART_FCR_ENABLE_FIFO;
>  	if (up->use_dma)
> @@ -677,6 +772,7 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
>  	 * Ok, we're now changing the port state. Do it with
>  	 * interrupts disabled.
>  	 */
> +	serial_omap_port_enable(up);
>  	spin_lock_irqsave(&up->port.lock, flags);
>  
>  	/*
> @@ -755,8 +851,11 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
>  	serial_out(up, UART_MCR, up->mcr);
>  
>  	/* Protocol, Baud Rate, and Interrupt Settings */
> +	if (up->errata & UART_ERRATA_i202_MDR1_ACCESS)
> +		omap_uart_mdr1_errataset(up);
> +	else
> +		serial_out(up, UART_OMAP_MDR1, up->mdr1);
>  
> -	serial_out(up, UART_OMAP_MDR1, UART_OMAP_MDR1_DISABLE);
>  	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
>  
>  	up->efr = serial_in(up, UART_EFR);
> @@ -766,8 +865,8 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
>  	serial_out(up, UART_IER, 0);
>  	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
>  
> -	serial_out(up, UART_DLL, quot & 0xff);          /* LS of divisor */
> -	serial_out(up, UART_DLM, quot >> 8);            /* MS of divisor */
> +	serial_out(up, UART_DLL, up->dll);	/* LS of divisor */
> +	serial_out(up, UART_DLM, up->dlh);	/* MS of divisor */
>  
>  	serial_out(up, UART_LCR, 0);
>  	serial_out(up, UART_IER, up->ier);
> @@ -777,9 +876,14 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
>  	serial_out(up, UART_LCR, cval);
>  
>  	if (baud > 230400 && baud != 3000000)
> -		serial_out(up, UART_OMAP_MDR1, UART_OMAP_MDR1_13X_MODE);
> +		up->mdr1 = UART_OMAP_MDR1_13X_MODE;
> +	else
> +		up->mdr1 = UART_OMAP_MDR1_16X_MODE;
> +
> +	if (up->errata & UART_ERRATA_i202_MDR1_ACCESS)
> +		omap_uart_mdr1_errataset(up);
>  	else
> -		serial_out(up, UART_OMAP_MDR1, UART_OMAP_MDR1_16X_MODE);
> +		serial_out(up, UART_OMAP_MDR1, up->mdr1);
>  
>  	/* Hardware Flow Control Configuration */
>  
> @@ -818,6 +922,8 @@ serial_omap_pm(struct uart_port *port, unsigned int state,
>  	unsigned char efr;
>  
>  	dev_dbg(up->port.dev, "serial_omap_pm+%d\n", up->pdev->id);
> +
> +	serial_omap_port_enable(up);
>  	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
>  	efr = serial_in(up, UART_EFR);
>  	serial_out(up, UART_EFR, efr | UART_EFR_ECB);
> @@ -827,6 +933,8 @@ serial_omap_pm(struct uart_port *port, unsigned int state,
>  	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
>  	serial_out(up, UART_EFR, efr);
>  	serial_out(up, UART_LCR, 0);
> +	if (state)
> +		serial_omap_port_disable(up);

FYI... this change doesn't apply when basing on the commit you mentioned
in PATCH 0/7.

>  }
>  
>  static void serial_omap_release_port(struct uart_port *port)
> @@ -904,6 +1012,8 @@ static inline void wait_for_xmitr(struct uart_omap_port *up)
>  static void serial_omap_poll_put_char(struct uart_port *port, unsigned char ch)
>  {
>  	struct uart_omap_port *up = (struct uart_omap_port *)port;
> +
> +	serial_omap_port_enable(up);
>  	wait_for_xmitr(up);
>  	serial_out(up, UART_TX, ch);
>  }
> @@ -911,8 +1021,10 @@ static void serial_omap_poll_put_char(struct uart_port *port, unsigned char ch)
>  static int serial_omap_poll_get_char(struct uart_port *port)
>  {
>  	struct uart_omap_port *up = (struct uart_omap_port *)port;
> -	unsigned int status = serial_in(up, UART_LSR);
> +	unsigned int status;
>  
> +	serial_omap_port_enable(up);
> +	status = serial_in(up, UART_LSR);
>  	if (!(status & UART_LSR_DR))
>  		return NO_POLL_CHAR;
>  
> @@ -922,7 +1034,6 @@ static int serial_omap_poll_get_char(struct uart_port *port)
>  #endif /* CONFIG_CONSOLE_POLL */
>  
>  #ifdef CONFIG_SERIAL_OMAP_CONSOLE
> -
>  static struct uart_omap_port *serial_omap_console_ports[4];
>  
>  static struct uart_driver serial_omap_reg;
> @@ -931,6 +1042,7 @@ static void serial_omap_console_putchar(struct uart_port *port, int ch)
>  {
>  	struct uart_omap_port *up = (struct uart_omap_port *)port;
>  
> +	serial_omap_port_enable(up);
>  	wait_for_xmitr(up);
>  	serial_out(up, UART_TX, ch);
>  }
> @@ -944,6 +1056,7 @@ serial_omap_console_write(struct console *co, const char *s,
>  	unsigned int ier;
>  	int locked = 1;
>  
> +	serial_omap_port_enable(up);
>  	local_irq_save(flags);
>  	if (up->port.sysrq)
>  		locked = 0;
> @@ -1058,22 +1171,25 @@ static struct uart_driver serial_omap_reg = {
>  	.cons		= OMAP_CONSOLE,
>  };
>  
> -static int
> -serial_omap_suspend(struct platform_device *pdev, pm_message_t state)
> +static int serial_omap_suspend(struct device *dev)
>  {
> -	struct uart_omap_port *up = platform_get_drvdata(pdev);
> +	struct uart_omap_port *up = dev_get_drvdata(dev);
>  
> -	if (up)
> +	if (up) {
>  		uart_suspend_port(&serial_omap_reg, &up->port);
> +		serial_omap_port_disable(up);
> +	}
> +
>  	return 0;
>  }
>  
> -static int serial_omap_resume(struct platform_device *dev)
> +static int serial_omap_resume(struct device *dev)
>  {
> -	struct uart_omap_port *up = platform_get_drvdata(dev);
> +	struct uart_omap_port *up = dev_get_drvdata(dev);
>  
>  	if (up)
>  		uart_resume_port(&serial_omap_reg, &up->port);
> +
>  	return 0;
>  }
>  
> @@ -1221,9 +1337,10 @@ static void uart_tx_dma_callback(int lch, u16 ch_status, void *data)
>  
>  static int serial_omap_probe(struct platform_device *pdev)
>  {
> -	struct uart_omap_port	*up;
> +	struct uart_omap_port	*up = NULL;
>  	struct resource		*mem, *irq, *dma_tx, *dma_rx;
>  	struct omap_uart_port_info *omap_up_info = pdev->dev.platform_data;
> +	struct omap_device *od;
>  	int ret = -ENOSPC;
>  
>  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> @@ -1273,12 +1390,23 @@ static int serial_omap_probe(struct platform_device *pdev)
>  	up->port.ops = &serial_omap_pops;
>  	up->port.line = pdev->id;
>  
> -	up->port.membase = omap_up_info->membase;
> -	up->port.mapbase = omap_up_info->mapbase;
> +	up->port.mapbase = mem->start;
> +	up->port.membase = ioremap(mem->start, mem->end - mem->start);
> +
> +	if (!up->port.membase) {
> +		dev_err(&pdev->dev, "can't ioremap UART\n");
> +		ret = -ENOMEM;
> +		goto err1;
> +	}
> +
>  	up->port.flags = omap_up_info->flags;
> -	up->port.irqflags = omap_up_info->irqflags;
>  	up->port.uartclk = omap_up_info->uartclk;
>  	up->uart_dma.uart_base = mem->start;
> +	up->errata = omap_up_info->errata;
> +
> +	up->wk_st = omap_up_info->wk_st;
> +	up->wk_en = omap_up_info->wk_en;
> +	up->wk_mask = omap_up_info->wk_mask;
>  
>  	if (omap_up_info->dma_enabled) {
>  		up->uart_dma.uart_dma_tx = dma_tx->start;
> @@ -1291,19 +1419,35 @@ static int serial_omap_probe(struct platform_device *pdev)
>  		up->uart_dma.tx_dma_channel = OMAP_UART_DMA_CH_FREE;
>  		up->uart_dma.rx_dma_channel = OMAP_UART_DMA_CH_FREE;
>  	}
> +	init_timer(&(up->inactivity_timer));
> +	up->inactivity_timer.function = serial_omap_inactivity_timer;
> +	up->inactivity_timer.data = up->pdev->id;
> +
> +	pm_runtime_enable(&pdev->dev);
> +	pm_runtime_irq_safe(&pdev->dev);

The changelog should describe why the IRQ-safe mode is needed.

> +	if (omap_up_info->console_uart) {
> +		od = container_of(pdev, struct omap_device, pdev);
> +		omap_hwmod_idle(od->hwmods[0]);

This was only in mach-omap2/serial.c because the early UART probing was
accessing registers.  With this driver becoming runtime PM aware, this
hack should not be needed, and the

	oh->flags |= HWMOD_INIT_NO_IDLE | HWMOD_INIT_NO_RESET;

should be removed from mach-omap2/serial.c

> +		serial_omap_port_enable(up);
> +	}
>  
>  	ui[pdev->id] = up;
>  	serial_omap_add_console_port(up);
>  
>  	ret = uart_add_one_port(&serial_omap_reg, &up->port);
>  	if (ret != 0)
> -		goto do_release_region;
> +		goto err1;
>  
> +	dev_set_drvdata(&pdev->dev, up);
>  	platform_set_drvdata(pdev, up);
> +
>  	return 0;
>  err:
>  	dev_err(&pdev->dev, "[UART%d]: failure [%s]: %d\n",
>  				pdev->id, __func__, ret);
> +err1:
> +	kfree(up);
>  do_release_region:
>  	release_mem_region(mem->start, (mem->end - mem->start) + 1);
>  	return ret;
> @@ -1315,20 +1459,138 @@ static int serial_omap_remove(struct platform_device *dev)
>  
>  	platform_set_drvdata(dev, NULL);
>  	if (up) {
> +		pm_runtime_disable(&up->pdev->dev);
>  		uart_remove_one_port(&serial_omap_reg, &up->port);
>  		kfree(up);
>  	}
>  	return 0;
>  }
>  
> +/*
> + * Work Around for Errata i202 (3430 - 1.12, 3630 - 1.6)
> + * The access to uart register after MDR1 Access
> + * causes UART to corrupt data.
> + *
> + * Need a delay =
> + * 5 L4 clock cycles + 5 UART functional clock cycle (@48MHz = ~0.2uS)
> + * give 10 times as much
> + */
> +static void omap_uart_mdr1_errataset(struct uart_omap_port *up)
> +{
> +	u8 timeout = 255;
> +
> +	serial_out(up, UART_OMAP_MDR1, up->mdr1);
> +	udelay(2);
> +	serial_out(up, UART_FCR, up->fcr | UART_FCR_CLEAR_XMIT |
> +			UART_FCR_CLEAR_RCVR);
> +	/*
> +	 * Wait for FIFO to empty: when empty, RX_FIFO_E bit is 0 and
> +	 * TX_FIFO_E bit is 1.
> +	 */
> +	while (UART_LSR_THRE != (serial_in(up, UART_LSR) &
> +				(UART_LSR_THRE | UART_LSR_DR))) {
> +		timeout--;
> +		if (!timeout) {
> +			/* Should *never* happen. we warn and carry on */
> +			dev_crit(&up->pdev->dev, "Errata i202: timedout %x\n",
> +			serial_in(up, UART_LSR));
> +			break;
> +		}
> +		udelay(1);
> +	}
> +}
> +
> +static void omap_uart_restore_context(struct uart_omap_port *up)
> +{
> +	u16 efr = 0;
> +
> +	if (up->errata & UART_ERRATA_i202_MDR1_ACCESS)
> +		omap_uart_mdr1_errataset(up);
> +	else
> +		serial_out(up, UART_OMAP_MDR1, up->mdr1);
> +	serial_out(up, UART_LCR, 0xBF); /* Config B mode */
> +	efr = serial_in(up, UART_EFR);
> +	serial_out(up, UART_EFR, UART_EFR_ECB);
> +	serial_out(up, UART_LCR, 0x0); /* Operational mode */
> +	serial_out(up, UART_IER, 0x0);
> +	serial_out(up, UART_LCR, 0xBF); /* Config B mode */
> +	serial_out(up, UART_DLL, up->dll);
> +	serial_out(up, UART_DLM, up->dlh);
> +	serial_out(up, UART_LCR, 0x0); /* Operational mode */
> +	serial_out(up, UART_IER, up->ier);
> +	serial_out(up, UART_FCR, up->fcr);
> +	serial_out(up, UART_LCR, 0x80);
> +	serial_out(up, UART_MCR, up->mcr);
> +	serial_out(up, UART_LCR, 0xBF); /* Config B mode */
> +	serial_out(up, UART_EFR, efr);
> +	serial_out(up, UART_LCR, UART_LCR_WLEN8);
> +	if (up->errata & UART_ERRATA_i202_MDR1_ACCESS)
> +		omap_uart_mdr1_errataset(up);
> +	else
> +		/* UART 16x mode */
> +		serial_out(up, UART_OMAP_MDR1, up->mdr1);
> +}
> +
> +static void omap_uart_enable_wakeup(struct uart_omap_port *up)
> +{
> +	/* Set wake-enable bit */
> +	if (up->wk_en && up->wk_mask) {
> +		u32 v = __raw_readl(up->wk_en);
> +		v |= up->wk_mask;
> +		__raw_writel(v, up->wk_en);
> +	}
> +}
> +
> +static void omap_uart_disable_wakeup(struct uart_omap_port *up)
> +{
> +	/* Clear wake-enable bit */
> +	if (up->wk_en && up->wk_mask) {
> +		u32 v = __raw_readl(up->wk_en);
> +		v &= ~up->wk_mask;
> +		__raw_writel(v, up->wk_en);
> +	}
> +}

Again, driver should not be doing direct PRCM accesses here. 

For now, how about leaving these also in mach-omap2/serial.c and calling
them via pdata function pointers:

  if (pdata->enable_wakeup)
      pdata->enable_wakeup()

> +static int omap_serial_runtime_suspend(struct device *dev)
> +{
> +	struct uart_omap_port *up = dev_get_drvdata(dev);
> +
> +	if (!up)
> +		goto done;
> +
> +	if (device_may_wakeup(&up->pdev->dev))
> +		omap_uart_enable_wakeup(up);
> +	else
> +		omap_uart_disable_wakeup(up);
> +done:
> +	return 0;
> +}
> +
> +static int omap_serial_runtime_resume(struct device *dev)
> +{
> +	struct uart_omap_port *up = dev_get_drvdata(dev);
> +
> +	if (!up)
> +		goto done;
> +
> +	omap_uart_restore_context(up);
> +done:
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops omap_serial_dev_pm_ops = {
> +	.suspend = serial_omap_suspend,
> +	.resume	= serial_omap_resume,
> +	.runtime_suspend = omap_serial_runtime_suspend,
> +	.runtime_resume = omap_serial_runtime_resume,
> +};
> +
>  static struct platform_driver serial_omap_driver = {
>  	.probe          = serial_omap_probe,
>  	.remove         = serial_omap_remove,
> -
> -	.suspend	= serial_omap_suspend,
> -	.resume		= serial_omap_resume,
>  	.driver		= {
>  		.name	= DRIVER_NAME,
> +		.pm = &omap_serial_dev_pm_ops,
>  	},
>  };

Kevin