Re: [PATCH v2 04/12] Serial: OMAP: Add runtime pm support for omap-serial driver

[Govindraj <govindraj.ti@gmail.com>]

On Thu, May 5, 2011 at 2:05 AM, Kevin Hilman <khilman@ti.com> wrote:
> "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.) Moving context_restore func to driver from serial.c
>> 3.) Adding port_enable/disable func to enable/disable given uart port.
>>     enable port using get_sync and disable using autosuspend.
>> 4.) using runtime irq safe api to make get_sync be called from irq context.
>>
>> Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
>> ---
>>  arch/arm/mach-omap2/serial.c                  |   16 ++
>>  arch/arm/plat-omap/include/plat/omap-serial.h |    2 +
>>  drivers/tty/serial/omap-serial.c              |  211 ++++++++++++++++++++++---
>>  3 files changed, 203 insertions(+), 26 deletions(-)
>>
>> diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
>> index 8c1a4c7..314d82f 100644
>> --- a/arch/arm/mach-omap2/serial.c
>> +++ b/arch/arm/mach-omap2/serial.c
>> @@ -189,6 +189,21 @@ static void omap_serial_fill_default_pads(struct omap_board_data *bdata)
>>       }
>>  }
>>
>> +static void omap_uart_wakeup_enable(struct platform_device *pdev, bool enable)
>> +{
>> +     struct omap_uart_port_info *up = pdev->dev.platform_data;
>> +
>> +     /* Set or clear wake-enable bit */
>> +     if (up->wk_en && up->wk_mask) {
>> +             u32 v = __raw_readl(up->wk_en);
>> +             if (enable)
>> +                     v |= up->wk_mask;
>> +             else
>> +                     v &= ~up->wk_mask;
>> +             __raw_writel(v, up->wk_en);
>> +     }
>> +}
>
> Rather than having the driver do this via the PRCM, can you do an
> experiment?  Can you try to leave the module-level wakeup enabled all
> the time in the PRCM, and the driver can then enable/disable
> module-level wakeups simply by toggling ENAWAKEUP in the module's
> SYSCONFIG?  If that works, than you can just use
> omap_hwmod_enable_wakeup() for this and not need the above function.
>

If we leave PRCM uart module level bit enabled all time and we disable
wakeup using sysfs

echo disabled > /sys/devices/platform/omap/omap_uart.0/power/wakeup

it wakes up after clock disable, however unsetting the bit ensures it doesn't
wakeup after uart clocks are cut.

As Paul suggested, How about adding omap_device/omap_hwmod function
to set and unset the bit?

Using

.module_bit = OMAP3430_EN_UART1_SHIFT,

from hwmod data?


>>  static void omap_uart_idle_init(struct omap_uart_port_info *uart,
>>                               unsigned short num)
>>  {
>> @@ -332,6 +347,7 @@ void __init omap_serial_init_port(struct omap_board_data *bdata)
>>
>>       pdata->uartclk = OMAP24XX_BASE_BAUD * 16;
>>       pdata->flags = UPF_BOOT_AUTOCONF;
>> +     pdata->enable_wakeup = omap_uart_wakeup_enable;
>>       if (bdata->id == omap_uart_con_id)
>>               pdata->console_uart = true;

<<SNIP>>

>> +     pm_runtime_use_autosuspend(&pdev->dev);
>> +     pm_runtime_set_autosuspend_delay(&pdev->dev,
>> +                     OMAP_UART_AUTOSUSPEND_DELAY);
>> +
>> +     pm_runtime_enable(&pdev->dev);
>> +     pm_runtime_irq_safe(&pdev->dev);
>> +
>> +     if (omap_up_info->console_uart) {
>> +             od = to_omap_device(up->pdev);
>> +             omap_hwmod_idle(od->hwmods[0]);
>
> Driver should have know knowlege of the underlying hwmod.
>
> I assume this is here because of the usage of HWMOD_INIT_NO_IDLE and
> HWMOD_INIT_NO_RESET, right?

 Yes correct.

> With proper runtime PM, we should be able to remove the need for using those flags.


For omap-uart used for earlyprintk's the early_console driver will
use printch from debug macro to print through uart.

During omap-hwmod is getting initialized

--> _setup
   --> _idle
    ---> _disable_clocks

at this point of time while printch is happening and
hwmod disables uart clocks I dont have uart-console
driver available which can enable clocks back.

So I have to use those flags when earlyprintk is enabled.

--
Thanks,
Govindraj.R


>
> Kevin
>
>> +             serial_omap_port_enable(up);
>> +             serial_omap_port_disable(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;
>> @@ -1318,20 +1421,76 @@ 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;
>>  }
>>
>> +static void omap_uart_restore_context(struct uart_omap_port *up)
>> +{
>> +     u16 efr = 0;
>> +
>> +     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);
>> +     /* UART 16x mode */
>> +     serial_out(up, UART_OMAP_MDR1, up->mdr1);
>> +}
>> +
>> +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(dev))
>> +             up->enable_wakeup(up->pdev, true);
>> +     else
>> +             up->enable_wakeup(up->pdev, false);
>> +done:
>> +     return 0;
>> +}
>> +
>> +static int omap_serial_runtime_resume(struct device *dev)
>> +{
>> +     struct uart_omap_port *up = dev_get_drvdata(dev);
>> +
>> +     if (up)
>> +             omap_uart_restore_context(up);
>> +
>> +     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,
>>       },
>>  };
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