* Paul Walmsley <paul@xxxxxxxxx> [080514 14:58]:
>
> The generic rwsem implementation of down_read() and down_write() does not
> save and restore interrupt state. This causes powerdomain code to
> inadvertently enable interrupts early in the boot process, causing
> init/main.c to complain. This patch converts powerdomain locking to
> r-w spinlocks instead.
>
> I'm also curious to know if this fixes the BeagleBoard boot problem.
Pushing today.
Tony
> Signed-off-by: Paul Walmsley <paul@xxxxxxxxx>
> ---
>
> arch/arm/mach-omap2/powerdomain.c | 46 ++++++++++++++++++++++---------------
> 1 files changed, 27 insertions(+), 19 deletions(-)
>
>
> diff --git a/arch/arm/mach-omap2/powerdomain.c b/arch/arm/mach-omap2/powerdomain.c
> index 939efe4..0a6caaf 100644
> --- a/arch/arm/mach-omap2/powerdomain.c
> +++ b/arch/arm/mach-omap2/powerdomain.c
> @@ -18,7 +18,7 @@
> #include <linux/module.h>
> #include <linux/types.h>
> #include <linux/delay.h>
> -#include <linux/rwsem.h>
> +#include <linux/spinlock.h>
> #include <linux/list.h>
> #include <linux/errno.h>
> #include <linux/err.h>
> @@ -38,10 +38,10 @@
> static LIST_HEAD(pwrdm_list);
>
> /*
> - * pwrdm_rwsem protects pwrdm_list add and del ops - also reused to
> + * pwrdm_rwlock protects pwrdm_list add and del ops - also reused to
> * protect pwrdm_clkdms[] during clkdm add/del ops
> */
> -static DECLARE_RWSEM(pwrdm_rwsem);
> +static DEFINE_RWLOCK(pwrdm_rwlock);
>
>
> /* Private functions */
> @@ -131,6 +131,7 @@ void pwrdm_init(struct powerdomain **pwrdm_list)
> */
> int pwrdm_register(struct powerdomain *pwrdm)
> {
> + unsigned long flags;
> int ret = -EINVAL;
>
> if (!pwrdm)
> @@ -139,7 +140,7 @@ int pwrdm_register(struct powerdomain *pwrdm)
> if (!omap_chip_is(pwrdm->omap_chip))
> return -EINVAL;
>
> - down_write(&pwrdm_rwsem);
> + write_lock_irqsave(&pwrdm_rwlock, flags);
> if (_pwrdm_lookup(pwrdm->name)) {
> ret = -EEXIST;
> goto pr_unlock;
> @@ -151,7 +152,7 @@ int pwrdm_register(struct powerdomain *pwrdm)
> ret = 0;
>
> pr_unlock:
> - up_write(&pwrdm_rwsem);
> + write_unlock_irqrestore(&pwrdm_rwlock, flags);
>
> return ret;
> }
> @@ -165,12 +166,14 @@ pr_unlock:
> */
> int pwrdm_unregister(struct powerdomain *pwrdm)
> {
> + unsigned long flags;
> +
> if (!pwrdm)
> return -EINVAL;
>
> - down_write(&pwrdm_rwsem);
> + write_lock_irqsave(&pwrdm_rwlock, flags);
> list_del(&pwrdm->node);
> - up_write(&pwrdm_rwsem);
> + write_unlock_irqrestore(&pwrdm_rwlock, flags);
>
> pr_debug("powerdomain: unregistered %s\n", pwrdm->name);
>
> @@ -187,13 +190,14 @@ int pwrdm_unregister(struct powerdomain *pwrdm)
> struct powerdomain *pwrdm_lookup(const char *name)
> {
> struct powerdomain *pwrdm;
> + unsigned long flags;
>
> if (!name)
> return NULL;
>
> - down_read(&pwrdm_rwsem);
> + read_lock_irqsave(&pwrdm_rwlock, flags);
> pwrdm = _pwrdm_lookup(name);
> - up_read(&pwrdm_rwsem);
> + read_unlock_irqrestore(&pwrdm_rwlock, flags);
>
> return pwrdm;
> }
> @@ -204,7 +208,7 @@ struct powerdomain *pwrdm_lookup(const char *name)
> *
> * Call the supplied function for each registered powerdomain. The
> * callback function can return anything but 0 to bail out early from
> - * the iterator. The callback function is called with the pwrdm_rwsem
> + * the iterator. The callback function is called with the pwrdm_rwlock
> * held for reading, so no powerdomain structure manipulation
> * functions should be called from the callback, although hardware
> * powerdomain control functions are fine. Returns the last return
> @@ -215,18 +219,19 @@ struct powerdomain *pwrdm_lookup(const char *name)
> int pwrdm_for_each(int (*fn)(struct powerdomain *pwrdm))
> {
> struct powerdomain *temp_pwrdm;
> + unsigned long flags;
> int ret = 0;
>
> if (!fn)
> return -EINVAL;
>
> - down_read(&pwrdm_rwsem);
> + read_lock_irqsave(&pwrdm_rwlock, flags);
> list_for_each_entry(temp_pwrdm, &pwrdm_list, node) {
> ret = (*fn)(temp_pwrdm);
> if (ret)
> break;
> }
> - up_read(&pwrdm_rwsem);
> + read_unlock_irqrestore(&pwrdm_rwlock, flags);
>
> return ret;
> }
> @@ -243,6 +248,7 @@ int pwrdm_for_each(int (*fn)(struct powerdomain *pwrdm))
> */
> int pwrdm_add_clkdm(struct powerdomain *pwrdm, struct clockdomain *clkdm)
> {
> + unsigned long flags;
> int i;
> int ret = -EINVAL;
>
> @@ -252,7 +258,7 @@ int pwrdm_add_clkdm(struct powerdomain *pwrdm, struct clockdomain *clkdm)
> pr_debug("powerdomain: associating clockdomain %s with powerdomain "
> "%s\n", clkdm->name, pwrdm->name);
>
> - down_write(&pwrdm_rwsem);
> + write_lock_irqsave(&pwrdm_rwlock, flags);
>
> for (i = 0; i < PWRDM_MAX_CLKDMS; i++) {
> if (!pwrdm->pwrdm_clkdms[i])
> @@ -278,7 +284,7 @@ int pwrdm_add_clkdm(struct powerdomain *pwrdm, struct clockdomain *clkdm)
> ret = 0;
>
> pac_exit:
> - up_write(&pwrdm_rwsem);
> + write_unlock_irqrestore(&pwrdm_rwlock, flags);
>
> return ret;
> }
> @@ -295,6 +301,7 @@ pac_exit:
> */
> int pwrdm_del_clkdm(struct powerdomain *pwrdm, struct clockdomain *clkdm)
> {
> + unsigned long flags;
> int ret = -EINVAL;
> int i;
>
> @@ -304,7 +311,7 @@ int pwrdm_del_clkdm(struct powerdomain *pwrdm, struct clockdomain *clkdm)
> pr_debug("powerdomain: dissociating clockdomain %s from powerdomain "
> "%s\n", clkdm->name, pwrdm->name);
>
> - down_write(&pwrdm_rwsem);
> + write_lock_irqsave(&pwrdm_rwlock, flags);
>
> for (i = 0; i < PWRDM_MAX_CLKDMS; i++)
> if (pwrdm->pwrdm_clkdms[i] == clkdm)
> @@ -322,7 +329,7 @@ int pwrdm_del_clkdm(struct powerdomain *pwrdm, struct clockdomain *clkdm)
> ret = 0;
>
> pdc_exit:
> - up_write(&pwrdm_rwsem);
> + write_unlock_irqrestore(&pwrdm_rwlock, flags);
>
> return ret;
> }
> @@ -335,7 +342,7 @@ pdc_exit:
> * Call the supplied function for each clockdomain in the powerdomain
> * 'pwrdm'. The callback function can return anything but 0 to bail
> * out early from the iterator. The callback function is called with
> - * the pwrdm_rwsem held for reading, so no powerdomain structure
> + * the pwrdm_rwlock held for reading, so no powerdomain structure
> * manipulation functions should be called from the callback, although
> * hardware powerdomain control functions are fine. Returns -EINVAL
> * if presented with invalid pointers; or passes along the last return
> @@ -346,18 +353,19 @@ int pwrdm_for_each_clkdm(struct powerdomain *pwrdm,
> int (*fn)(struct powerdomain *pwrdm,
> struct clockdomain *clkdm))
> {
> + unsigned long flags;
> int ret = 0;
> int i;
>
> if (!fn)
> return -EINVAL;
>
> - down_read(&pwrdm_rwsem);
> + read_lock_irqsave(&pwrdm_rwlock, flags);
>
> for (i = 0; i < PWRDM_MAX_CLKDMS && !ret; i++)
> ret = (*fn)(pwrdm, pwrdm->pwrdm_clkdms[i]);
>
> - up_read(&pwrdm_rwsem);
> + read_unlock_irqrestore(&pwrdm_rwlock, flags);
>
> return ret;
> }
> --
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