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author | Boris Brezillon <boris.brezillon@bootlin.com> | 2018-11-20 11:57:20 +0100 |
---|---|---|
committer | Miquel Raynal <miquel.raynal@bootlin.com> | 2019-02-05 15:39:40 +0100 |
commit | 013e6292aaf5e4b083a50a0f9e17e93628616860 (patch) | |
tree | a15ef0c0f41fb1c14a283e9969a6aab719050ec0 | |
parent | 661803b23330daa7839680cca43ab410955c3f10 (diff) | |
download | linux-013e6292aaf5e4b083a50a0f9e17e93628616860.tar.bz2 |
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 <boris.brezillon@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
-rw-r--r-- | drivers/mtd/nand/raw/nand_base.c | 111 | ||||
-rw-r--r-- | include/linux/mtd/rawnand.h | 24 |
2 files changed, 54 insertions, 81 deletions
diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index cca4b24d2ffa..96cadead262e 100644 --- a/drivers/mtd/nand/raw/nand_base.c +++ b/drivers/mtd/nand/raw/nand_base.c @@ -278,11 +278,8 @@ EXPORT_SYMBOL_GPL(nand_deselect_target); static void nand_release_device(struct nand_chip *chip) { /* Release the controller and the chip */ - spin_lock(&chip->controller->lock); - chip->controller->active = NULL; - chip->state = FL_READY; - wake_up(&chip->controller->wq); - spin_unlock(&chip->controller->lock); + mutex_unlock(&chip->controller->lock); + mutex_unlock(&chip->lock); } /** @@ -331,57 +328,23 @@ static int nand_isbad_bbm(struct nand_chip *chip, loff_t ofs) } /** - * panic_nand_get_device - [GENERIC] Get chip for selected access - * @chip: the nand chip descriptor - * @new_state: the state which is requested - * - * Used when in panic, no locks are taken. - */ -static void panic_nand_get_device(struct nand_chip *chip, int new_state) -{ - /* Hardware controller shared among independent devices */ - chip->controller->active = chip; - chip->state = new_state; -} - -/** * nand_get_device - [GENERIC] Get chip for selected access * @chip: NAND chip structure - * @new_state: the state which is requested * - * Get the device and lock it for exclusive access + * Lock the device and its controller for exclusive access + * + * Return: -EBUSY if the chip has been suspended, 0 otherwise */ -static int -nand_get_device(struct nand_chip *chip, int new_state) +static int nand_get_device(struct nand_chip *chip) { - spinlock_t *lock = &chip->controller->lock; - wait_queue_head_t *wq = &chip->controller->wq; - DECLARE_WAITQUEUE(wait, current); -retry: - spin_lock(lock); - - /* Hardware controller shared among independent devices */ - if (!chip->controller->active) - chip->controller->active = chip; - - if (chip->controller->active == chip && chip->state == FL_READY) { - chip->state = new_state; - spin_unlock(lock); - return 0; - } - if (new_state == FL_PM_SUSPENDED) { - if (chip->controller->active->state == FL_PM_SUSPENDED) { - chip->state = FL_PM_SUSPENDED; - spin_unlock(lock); - return 0; - } + mutex_lock(&chip->lock); + if (chip->suspended) { + mutex_unlock(&chip->lock); + return -EBUSY; } - set_current_state(TASK_UNINTERRUPTIBLE); - add_wait_queue(wq, &wait); - spin_unlock(lock); - schedule(); - remove_wait_queue(wq, &wait); - goto retry; + mutex_lock(&chip->controller->lock); + + return 0; } /** @@ -602,7 +565,10 @@ static int nand_block_markbad_lowlevel(struct nand_chip *chip, loff_t ofs) nand_erase_nand(chip, &einfo, 0); /* Write bad block marker to OOB */ - nand_get_device(chip, FL_WRITING); + ret = nand_get_device(chip); + if (ret) + return ret; + ret = nand_markbad_bbm(chip, ofs); nand_release_device(chip); } @@ -3580,7 +3546,9 @@ static int nand_read_oob(struct mtd_info *mtd, loff_t from, ops->mode != MTD_OPS_RAW) return -ENOTSUPP; - nand_get_device(chip, FL_READING); + ret = nand_get_device(chip); + if (ret) + return ret; if (!ops->datbuf) ret = nand_do_read_oob(chip, from, ops); @@ -4099,9 +4067,6 @@ static int panic_nand_write(struct mtd_info *mtd, loff_t to, size_t len, struct mtd_oob_ops ops; int ret; - /* Grab the device */ - panic_nand_get_device(chip, FL_WRITING); - nand_select_target(chip, chipnr); /* Wait for the device to get ready */ @@ -4132,7 +4097,9 @@ static int nand_write_oob(struct mtd_info *mtd, loff_t to, ops->retlen = 0; - nand_get_device(chip, FL_WRITING); + ret = nand_get_device(chip); + if (ret) + return ret; switch (ops->mode) { case MTD_OPS_PLACE_OOB: @@ -4205,7 +4172,9 @@ int nand_erase_nand(struct nand_chip *chip, struct erase_info *instr, return -EINVAL; /* Grab the lock and see if the device is available */ - nand_get_device(chip, FL_ERASING); + ret = nand_get_device(chip); + if (ret) + return ret; /* Shift to get first page */ page = (int)(instr->addr >> chip->page_shift); @@ -4298,7 +4267,7 @@ static void nand_sync(struct mtd_info *mtd) pr_debug("%s: called\n", __func__); /* Grab the lock and see if the device is available */ - nand_get_device(chip, FL_SYNCING); + WARN_ON(nand_get_device(chip)); /* Release it and go back */ nand_release_device(chip); } @@ -4315,7 +4284,10 @@ static int nand_block_isbad(struct mtd_info *mtd, loff_t offs) int ret; /* Select the NAND device */ - nand_get_device(chip, FL_READING); + ret = nand_get_device(chip); + if (ret) + return ret; + nand_select_target(chip, chipnr); ret = nand_block_checkbad(chip, offs, 0); @@ -4388,7 +4360,13 @@ static int nand_max_bad_blocks(struct mtd_info *mtd, loff_t ofs, size_t len) */ static int nand_suspend(struct mtd_info *mtd) { - return nand_get_device(mtd_to_nand(mtd), FL_PM_SUSPENDED); + struct nand_chip *chip = mtd_to_nand(mtd); + + mutex_lock(&chip->lock); + chip->suspended = 1; + mutex_unlock(&chip->lock); + + return 0; } /** @@ -4399,11 +4377,13 @@ static void nand_resume(struct mtd_info *mtd) { struct nand_chip *chip = mtd_to_nand(mtd); - if (chip->state == FL_PM_SUSPENDED) - nand_release_device(chip); + mutex_lock(&chip->lock); + if (chip->suspended) + chip->suspended = 0; else pr_err("%s called for a chip which is not in suspended state\n", __func__); + mutex_unlock(&chip->lock); } /** @@ -4413,7 +4393,7 @@ static void nand_resume(struct mtd_info *mtd) */ static void nand_shutdown(struct mtd_info *mtd) { - nand_get_device(mtd_to_nand(mtd), FL_PM_SUSPENDED); + nand_suspend(mtd); } /* Set default functions */ @@ -5018,6 +4998,8 @@ static int nand_scan_ident(struct nand_chip *chip, unsigned int maxchips, /* Assume all dies are deselected when we enter nand_scan_ident(). */ chip->cur_cs = -1; + mutex_init(&chip->lock); + /* Enforce the right timings for reset/detection */ onfi_fill_data_interface(chip, NAND_SDR_IFACE, 0); @@ -5717,9 +5699,6 @@ static int nand_scan_tail(struct nand_chip *chip) } chip->subpagesize = mtd->writesize >> mtd->subpage_sft; - /* Initialize state */ - chip->state = FL_READY; - /* Invalidate the pagebuffer reference */ chip->pagebuf = -1; 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 <linux/wait.h> -#include <linux/spinlock.h> #include <linux/mtd/mtd.h> #include <linux/mtd/flashchip.h> #include <linux/mtd/bbm.h> #include <linux/mtd/jedec.h> #include <linux/mtd/onfi.h> +#include <linux/mutex.h> #include <linux/of.h> #include <linux/types.h> @@ -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; |