From c3c1250e93a7ab1327a9fc49d2a22405672f4204 Mon Sep 17 00:00:00 2001 From: Ohad Ben-Cohen Date: Mon, 5 Sep 2011 23:15:06 +0300 Subject: hwspinlock/core/omap: fix id issues on multiple hwspinlock devices hwspinlock devices provide system-wide hardware locks that are used by remote processors that have no other way to achieve synchronization. To achieve that, each physical lock must have a system-wide id number that is agreed upon, otherwise remote processors can't possibly assume they're using the same hardware lock. Usually boards have a single hwspinlock device, which provides several hwspinlocks, and in this case, they can be trivially numbered 0 to (num-of-locks - 1). In case boards have several hwspinlocks devices, a different base id should be used for each hwspinlock device (they can't all use 0 as a starting id!). While this is certainly not common, it's just plain wrong to just silently use 0 as a base id whenever the hwspinlock driver is probed. This patch provides a hwspinlock_pdata structure, that boards can use to set a different base id for each of the hwspinlock devices they may have, and demonstrates how to use it with the omap hwspinlock driver. While we're at it, make sure the hwspinlock core prints an explicit error message in case an hwspinlock is registered with an id number that already exists; this will help users catch such base id issues. Reported-by: Arnd Bergmann Signed-off-by: Ohad Ben-Cohen Acked-by: Tony Lindgren --- include/linux/hwspinlock.h | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'include') diff --git a/include/linux/hwspinlock.h b/include/linux/hwspinlock.h index 8390efc457e..f85cef5452f 100644 --- a/include/linux/hwspinlock.h +++ b/include/linux/hwspinlock.h @@ -27,6 +27,34 @@ struct hwspinlock; +/** + * struct hwspinlock_pdata - platform data for hwspinlock drivers + * @base_id: base id for this hwspinlock device + * + * hwspinlock devices provide system-wide hardware locks that are used + * by remote processors that have no other way to achieve synchronization. + * + * To achieve that, each physical lock must have a system-wide id number + * that is agreed upon, otherwise remote processors can't possibly assume + * they're using the same hardware lock. + * + * Usually boards have a single hwspinlock device, which provides several + * hwspinlocks, and in this case, they can be trivially numbered 0 to + * (num-of-locks - 1). + * + * In case boards have several hwspinlocks devices, a different base id + * should be used for each hwspinlock device (they can't all use 0 as + * a starting id!). + * + * This platform data structure should be used to provide the base id + * for each device (which is trivially 0 when only a single hwspinlock + * device exists). It can be shared between different platforms, hence + * its location. + */ +struct hwspinlock_pdata { + int base_id; +}; + #if defined(CONFIG_HWSPINLOCK) || defined(CONFIG_HWSPINLOCK_MODULE) int hwspin_lock_register(struct hwspinlock *lock); -- cgit v1.2.3-18-g5258 From c536abfdf5227987b8a72ff955b64e62fd58fe91 Mon Sep 17 00:00:00 2001 From: Ohad Ben-Cohen Date: Thu, 8 Sep 2011 21:16:17 +0300 Subject: hwspinlock/core: remove stubs for register/unregister hwspinlock drivers must anyway select CONFIG_HWSPINLOCK, so there's no point in having register/unregister stubs. Removing those stubs will only make it easier for developers to catch CONFIG_HWSPINLOCK mis-.config-urations. Signed-off-by: Ohad Ben-Cohen --- include/linux/hwspinlock.h | 10 ---------- 1 file changed, 10 deletions(-) (limited to 'include') diff --git a/include/linux/hwspinlock.h b/include/linux/hwspinlock.h index f85cef5452f..c246522a955 100644 --- a/include/linux/hwspinlock.h +++ b/include/linux/hwspinlock.h @@ -122,16 +122,6 @@ static inline int hwspin_lock_get_id(struct hwspinlock *hwlock) return 0; } -static inline int hwspin_lock_register(struct hwspinlock *hwlock) -{ - return -ENODEV; -} - -static inline struct hwspinlock *hwspin_lock_unregister(unsigned int id) -{ - return NULL; -} - #endif /* !CONFIG_HWSPINLOCK */ /** -- cgit v1.2.3-18-g5258 From 300bab9770e2bd10262bcc78e7249fdce2c74b38 Mon Sep 17 00:00:00 2001 From: Ohad Ben-Cohen Date: Tue, 6 Sep 2011 15:39:21 +0300 Subject: hwspinlock/core: register a bank of hwspinlocks in a single API call Hardware Spinlock devices usually contain numerous locks (known devices today support between 32 to 256 locks). Originally hwspinlock core required drivers to register (and later, when needed, unregister) each lock separately. That worked, but required hwspinlocks drivers to do a bit extra work when they were probed/removed. This patch changes hwspin_lock_{un}register() to allow a bank of hwspinlocks to be {un}registered in a single invocation. A new 'struct hwspinlock_device', which contains an array of 'struct hwspinlock's is now being passed to the core upon registration (so instead of wrapping each struct hwspinlock, a priv member has been added to allow drivers to piggyback their private data with each hwspinlock). While at it, several per-lock members were moved to be per-device: 1. struct device *dev 2. struct hwspinlock_ops *ops In addition, now that the array of locks is handled by the core, there's no reason to maintain a per-lock 'int id' member: the id of the lock anyway equals to its index in the bank's array plus the bank's base_id. Remove this per-lock id member too, and instead use a simple pointers arithmetic to derive it. As a result of this change, hwspinlocks drivers are now simpler and smaller (about %20 code reduction) and the memory footprint of the hwspinlock framework is reduced. Signed-off-by: Ohad Ben-Cohen --- include/linux/hwspinlock.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/linux/hwspinlock.h b/include/linux/hwspinlock.h index c246522a955..08a2fee4065 100644 --- a/include/linux/hwspinlock.h +++ b/include/linux/hwspinlock.h @@ -20,12 +20,15 @@ #include #include +#include /* hwspinlock mode argument */ #define HWLOCK_IRQSTATE 0x01 /* Disable interrupts, save state */ #define HWLOCK_IRQ 0x02 /* Disable interrupts, don't save state */ struct hwspinlock; +struct hwspinlock_device; +struct hwspinlock_ops; /** * struct hwspinlock_pdata - platform data for hwspinlock drivers @@ -57,8 +60,9 @@ struct hwspinlock_pdata { #if defined(CONFIG_HWSPINLOCK) || defined(CONFIG_HWSPINLOCK_MODULE) -int hwspin_lock_register(struct hwspinlock *lock); -struct hwspinlock *hwspin_lock_unregister(unsigned int id); +int hwspin_lock_register(struct hwspinlock_device *bank, struct device *dev, + const struct hwspinlock_ops *ops, int base_id, int num_locks); +int hwspin_lock_unregister(struct hwspinlock_device *bank); struct hwspinlock *hwspin_lock_request(void); struct hwspinlock *hwspin_lock_request_specific(unsigned int id); int hwspin_lock_free(struct hwspinlock *hwlock); -- cgit v1.2.3-18-g5258