Add support to the atmel-mci driver for a VCC pin in order to conserve
power if the MMC interface is powered down.
Please read the whole set, try it out, and comment.
Thank you,
Rob Emanuele
---
drivers/mmc/host/atmel-mci.c | 33 ++++++++++++++++++++-------------
include/linux/atmel-mci.h | 2 ++
2 files changed, 22 insertions(+), 13 deletions(-)
diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
index 1c1a4b3..a639b93 100644
--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -214,6 +214,8 @@ struct atmel_mci_slot {
int detect_pin;
int wp_pin;
+ int vcc_pin;
+ bool vcc_pin_act_low;
struct timer_list detect_timer;
};
@@ -926,23 +928,19 @@ static void atmci_set_ios(struct mmc_host *mmc,
struct mmc_ios *ios)
}
switch (ios->power_mode) {
+ case MMC_POWER_OFF:
+ if (gpio_is_valid(slot->vcc_pin))
+ gpio_set_value(slot->vcc_pin, slot->vcc_pin_act_low);
+ break;
case MMC_POWER_UP:
+ if (gpio_is_valid(slot->vcc_pin))
+ gpio_set_value(slot->vcc_pin, !slot->vcc_pin_act_low);
set_bit(ATMCI_CARD_NEED_INIT, &slot->flags);
break;
- default:
- /*
- * TODO: None of the currently available AVR32-based
- * boards allow MMC power to be turned off. Implement
- * power control when this can be tested properly.
- *
- * We also need to hook this into the clock management
- * somehow so that newly inserted cards aren't
- * subjected to a fast clock before we have a chance
- * to figure out what the maximum rate is. Currently,
- * there's no way to avoid this, and there never will
- * be for boards that don't support power control.
- */
+ case MMC_POWER_ON:
break;
+ default:
+ WARN_ON(1);
}
}
@@ -1498,6 +1496,8 @@ static int __init atmci_init_slot(struct atmel_mci *host,
slot->host = host;
slot->detect_pin = slot_data->detect_pin;
slot->wp_pin = slot_data->wp_pin;
+ slot->vcc_pin = slot_data->vcc_pin;
+ slot->vcc_pin_act_low = slot_data->vcc_pin_act_low;
slot->sdc_reg = sdc_reg;
mmc->ops = &atmci_ops;
@@ -1534,6 +1534,13 @@ static int __init atmci_init_slot(struct atmel_mci *host,
}
}
+ if (gpio_is_valid(slot->vcc_pin)) {
+ if (gpio_request(slot->vcc_pin, "mmc_pow")) {
+ dev_dbg(&mmc->class_dev, "no power pin available\n");
+ slot->vcc_pin = -EBUSY;
+ }
+ }
+
host->slot[id] = slot;
mmc_add_host(mmc);
diff --git a/include/linux/atmel-mci.h b/include/linux/atmel-mci.h
index 2f1f957..3b4239a 100644
--- a/include/linux/atmel-mci.h
+++ b/include/linux/atmel-mci.h
@@ -24,6 +24,8 @@ struct mci_slot_pdata {
unsigned int bus_width;
int detect_pin;
int wp_pin;
+ int vcc_pin;
+ unsigned vcc_pin_act_low:1;
};
/**
--
1.6.0.4
Rob Emanuele :
> Add support to the atmel-mci driver for a VCC pin in order to conserve
> power if the MMC interface is powered down.
Can you elaborate a bit more. In particular, I do not understand the
concept of "vcc_pin_act_low".
[..]
Thanks. Bye,
--
Nicolas Ferre
Nicolas,
On Mon, Jun 15, 2009 at 9:20 AM, Nicolas Ferre<[email protected]> wrote:
> Rob Emanuele :
>> Add support to the atmel-mci driver for a VCC pin in order to conserve
>> power if the MMC interface is powered down.
>
> Can you elaborate a bit more. In particular, I do not understand the
> concept of "vcc_pin_act_low".
>
Like the original at91_mci driver, this patch adds the ability to use
a pin to toggle 3.3V power going to the SD Card. In my case the pin
is tied to a International Rectifier 6420 P-type MOSFET since a port
pin alone cannot drive the SD Card. When I pull the vcc_pin low, 3.3V
can reach the SD Card to power it. The "vcc_pin_act_low" (pin active
low) determines which way the pin should be pulled to enable power to
the SD Card. If vcc_pin_act_low is true, when the card needs to get
powered up, it sets the vcc_pin low. Other board designs may need a
pin driven high to power the SD Card.
Thanks,
Rob
> diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
> index 1c1a4b3..a639b93 100644
> --- a/drivers/mmc/host/atmel-mci.c
> +++ b/drivers/mmc/host/atmel-mci.c
> @@ -214,6 +214,8 @@ struct atmel_mci_slot {
>
> int detect_pin;
> int wp_pin;
> + int vcc_pin;
> + bool vcc_pin_act_low;
Maybe, just 'vcc_active_low' is more clear?
Most other kernel code use 'active_low' or 'xyz_active_low' as far as I can
see.
That would be fine with me.
On Mon, Jun 15, 2009 at 2:35 PM, Michael Roth<[email protected]> wrote:
>
>> diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
>> index 1c1a4b3..a639b93 100644
>> --- a/drivers/mmc/host/atmel-mci.c
>> +++ b/drivers/mmc/host/atmel-mci.c
>> @@ -214,6 +214,8 @@ struct atmel_mci_slot {
>>
>> ? ? ? int ? ? ? ? ? ? ? ? ? ? detect_pin;
>> ? ? ? int ? ? ? ? ? ? ? ? ? ? wp_pin;
>> + ? ? int ? ? ? ? ? ? ? ? ? ? vcc_pin;
>> + ? ? bool ? ? ? ? ? ? ? ? ? ?vcc_pin_act_low;
>
> Maybe, just 'vcc_active_low' is more clear?
>
> Most other kernel code use 'active_low' or 'xyz_active_low' as far as I can
> see.
>
>