On Fri, Mar 15, 2013 at 09:00:35AM -0400, Eduardo Valentin wrote:
> Because there is a need to lock inside IRQ handler, this patch
> changes the locking mechanism inside the omap-bandgap.[c,h] to
> spinlocks. Now this lock is used to protect omap_bandgap struct
> during APIs exposed (possibly used in sysfs handling functions)
> and inside the ALERT IRQ handler.
>
> Because there are registers shared among the sensors, this lock
> is global, not per sensor.
>
> Signed-off-by: Eduardo Valentin <eduardo.valentin@xxxxxx>
> ---
> drivers/staging/omap-thermal/TODO | 1 -
> drivers/staging/omap-thermal/omap-bandgap.c | 18 ++++++++++--------
> drivers/staging/omap-thermal/omap-bandgap.h | 4 ++--
> 3 files changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/staging/omap-thermal/TODO b/drivers/staging/omap-thermal/TODO
> index 77b761b..0f24e9b 100644
> --- a/drivers/staging/omap-thermal/TODO
> +++ b/drivers/staging/omap-thermal/TODO
> @@ -1,7 +1,6 @@
> List of TODOs (by Eduardo Valentin)
>
> on omap-bandgap.c:
> -- Rework locking
> - Improve driver code by adding usage of regmap-mmio
> - Test every exposed API to userland
> - Add support to hwmon
> diff --git a/drivers/staging/omap-thermal/omap-bandgap.c b/drivers/staging/omap-thermal/omap-bandgap.c
> index 4b631fd..846ced6 100644
> --- a/drivers/staging/omap-thermal/omap-bandgap.c
> +++ b/drivers/staging/omap-thermal/omap-bandgap.c
> @@ -33,7 +33,7 @@
> #include <linux/platform_device.h>
> #include <linux/err.h>
> #include <linux/types.h>
> -#include <linux/mutex.h>
> +#include <linux/spinlock.h>
> #include <linux/reboot.h>
> #include <linux/of_device.h>
> #include <linux/of_platform.h>
> @@ -170,6 +170,7 @@ static irqreturn_t omap_bandgap_talert_irq_handler(int irq, void *data)
> u32 t_hot = 0, t_cold = 0, ctrl;
> int i;
>
> + spin_lock(&bg_ptr->lock);
> for (i = 0; i < bg_ptr->conf->sensor_count; i++) {
> tsr = bg_ptr->conf->sensors[i].registers;
> ctrl = omap_bandgap_readl(bg_ptr, tsr->bgap_status);
> @@ -208,6 +209,7 @@ static irqreturn_t omap_bandgap_talert_irq_handler(int irq, void *data)
> if (bg_ptr->conf->report_temperature)
> bg_ptr->conf->report_temperature(bg_ptr, i);
> }
> + spin_unlock(&bg_ptr->lock);
>
> return IRQ_HANDLED;
> }
> @@ -502,9 +504,9 @@ int _omap_bandgap_write_threshold(struct omap_bandgap *bg_ptr, int id, int val,
> if (ret < 0)
> goto exit;
>
> - mutex_lock(&bg_ptr->bg_mutex);
> + spin_lock(&bg_ptr->lock);
These need to disable interrupts because we take the spin lock in
the IRQ handler.
regards,
dan carpenter
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