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mmc: omap_hsmmc: Pin remux workaround to support SDIO interrupt on AM335x 

The am335x can't detect pending cirq in PM runtime suspend.
This patch reconfigures dat1 as a GPIO before going to suspend.
SDIO interrupts are detected with the GPIO, the GPIO will only wake
the module from suspend, SDIO irq detection will still happen through the
IP block.

Idea of remuxing the pins by Tony Lindgren. Code contributions from
Tony Lindgren and Balaji T K <balajitk@ti.com>

Signed-off-by: Andreas Fenkart <afenkart@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Acked-by: Balaji T K <balajitk@ti.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Andreas Fenkart 2014-05-29 10:28:05 +02:00 committed by Ulf Hansson
parent 97978a4439
commit 455e5cd6f7
2 changed files with 74 additions and 3 deletions
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53
Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt
View File

@ -57,3 +57,56 @@ Examples:
&edma 25>;
dma-names = "tx", "rx";
};
[workaround for missing swakeup on am33xx]
This SOC is missing the swakeup line, it will not detect SDIO irq
while in suspend.
------
| PRCM |
------
^ |
swakeup | | fclk
| v
------ ------- -----
| card | -- CIRQ --> | hsmmc | -- IRQ --> | CPU |
------ ------- -----
In suspend the fclk is off and the module is disfunctional. Even register reads
will fail. A small logic in the host will request fclk restore, when an
external event is detected. Once the clock is restored, the host detects the
event normally. Since am33xx doesn't have this line it never wakes from
suspend.
The workaround is to reconfigure the dat1 line as a GPIO upon suspend. To make
this work, we need to set the named pinctrl states "default" and "idle".
Prepare idle to remux dat1 as a gpio, and default to remux it back as sdio
dat1. The MMC driver will then toggle between idle and default state during
runtime.
In summary:
1. select matching 'compatible' section, see example below.
2. specify pinctrl states "default" and "idle", "sleep" is optional.
3. specify the gpio irq used for detecting sdio irq in suspend
If configuration is incomplete, a warning message is emitted "falling back to
polling". Also check the "sdio irq mode" in /sys/kernel/debug/mmc0/regs. Mind
not every application needs SDIO irq, e.g. MMC cards.
mmc1: mmc@48060100 {
compatible = "ti,am33xx-hsmmc";
...
pinctrl-names = "default", "idle", "sleep"
pinctrl-0 = <&mmc1_pins>;
pinctrl-1 = <&mmc1_idle>;
pinctrl-2 = <&mmc1_sleep>;
...
interrupts-extended = <&intc 64 &gpio2 28 0>;
};
mmc1_idle : pinmux_cirq_pin {
pinctrl-single,pins = <
0x0f8 0x3f /* GPIO2_28 */
>;
};

24
drivers/mmc/host/omap_hsmmc.c
View File

@ -1754,15 +1754,33 @@ static int omap_hsmmc_configure_wake_irq(struct omap_hsmmc_host *host)
* and need to remux SDIO DAT1 to GPIO for wake-up from idle.
*/
if (host->pdata->controller_flags & OMAP_HSMMC_SWAKEUP_MISSING) {
ret = -ENODEV;
devm_free_irq(host->dev, host->wake_irq, host);
goto err;
struct pinctrl *p = devm_pinctrl_get(host->dev);
if (!p) {
ret = -ENODEV;
goto err_free_irq;
}
if (IS_ERR(pinctrl_lookup_state(p, PINCTRL_STATE_DEFAULT))) {
dev_info(host->dev, "missing default pinctrl state\n");
devm_pinctrl_put(p);
ret = -EINVAL;
goto err_free_irq;
}
if (IS_ERR(pinctrl_lookup_state(p, PINCTRL_STATE_IDLE))) {
dev_info(host->dev, "missing idle pinctrl state\n");
devm_pinctrl_put(p);
ret = -EINVAL;
goto err_free_irq;
}
devm_pinctrl_put(p);
}
OMAP_HSMMC_WRITE(host->base, HCTL,
OMAP_HSMMC_READ(host->base, HCTL) | IWE);
return 0;
err_free_irq:
devm_free_irq(host->dev, host->wake_irq, host);
err:
dev_warn(host->dev, "no SDIO IRQ support, falling back to polling\n");
host->wake_irq = 0;