From 013e6292aaf5e4b083a50a0f9e17e93628616860 Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Tue, 20 Nov 2018 11:57:20 +0100 Subject: mtd: rawnand: Simplify the locking nand_get_device() was complex for apparently no good reason. Let's replace this locking scheme with 2 mutexes: one attached to the controller and another one attached to the chip. Every time the core calls nand_get_device(), it will first lock the chip and if the chip is not suspended, will then lock the controller. nand_release_device() will release both lock in the reverse order. nand_get_device() can sleep, just like the previous implementation, which means you should never call that from an atomic context. We also get rid of - the chip->state field, since all it was used for was flagging the chip as suspended. We replace it by a field called chip->suspended and directly set it from nand_suspend/resume() - the controller->wq and controller->active fields which are no longer needed since the new controller->lock (now a mutex) guarantees that all operations are serialized at the controller level - panic_nand_get_device() which would anyway be a no-op. Talking about panic write, I keep thinking the rawnand implementation is unsafe because there's not negotiation with the controller to know when it's actually done with it's previous operation. I don't intend to fix that here, but that's probably something we should look at, or maybe we should consider dropping the ->_panic_write() implementation Last important change to mention: we now return -EBUSY when someone tries to access a device that as been suspended, and propagate this error to the upper layer. Signed-off-by: Boris Brezillon Signed-off-by: Miquel Raynal --- include/linux/mtd/rawnand.h | 24 +++++++++--------------- 1 file changed, 9 insertions(+), 15 deletions(-) (limited to 'include/linux/mtd') diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h index 33e240acdc6d..17d2d9ae33bf 100644 --- a/include/linux/mtd/rawnand.h +++ b/include/linux/mtd/rawnand.h @@ -16,13 +16,12 @@ #ifndef __LINUX_MTD_RAWNAND_H #define __LINUX_MTD_RAWNAND_H -#include -#include #include #include #include #include #include +#include #include #include @@ -897,25 +896,17 @@ struct nand_controller_ops { /** * struct nand_controller - Structure used to describe a NAND controller * - * @lock: protection lock - * @active: the mtd device which holds the controller currently - * @wq: wait queue to sleep on if a NAND operation is in - * progress used instead of the per chip wait queue - * when a hw controller is available. + * @lock: lock used to serialize accesses to the NAND controller * @ops: NAND controller operations. */ struct nand_controller { - spinlock_t lock; - struct nand_chip *active; - wait_queue_head_t wq; + struct mutex lock; const struct nand_controller_ops *ops; }; static inline void nand_controller_init(struct nand_controller *nfc) { - nfc->active = NULL; - spin_lock_init(&nfc->lock); - init_waitqueue_head(&nfc->wq); + mutex_init(&nfc->lock); } /** @@ -983,7 +974,6 @@ struct nand_legacy { * setting the read-retry mode. Mostly needed for MLC NAND. * @ecc: [BOARDSPECIFIC] ECC control structure * @buf_align: minimum buffer alignment required by a platform - * @state: [INTERN] the current state of the NAND device * @oob_poi: "poison value buffer," used for laying out OOB data * before writing * @page_shift: [INTERN] number of address bits in a page (column @@ -1034,6 +1024,9 @@ struct nand_legacy { * cur_cs < numchips. NAND Controller drivers should not * modify this value, but they're allowed to read it. * @read_retries: [INTERN] the number of read retry modes supported + * @lock: lock protecting the suspended field. Also used to + * serialize accesses to the NAND device. + * @suspended: set to 1 when the device is suspended, 0 when it's not. * @bbt: [INTERN] bad block table pointer * @bbt_td: [REPLACEABLE] bad block table descriptor for flash * lookup. @@ -1088,7 +1081,8 @@ struct nand_chip { int read_retries; - flstate_t state; + struct mutex lock; + unsigned int suspended : 1; uint8_t *oob_poi; struct nand_controller *controller; -- cgit