@@ -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);
}
/**
@@ -330,58 +327,24 @@ static int nand_isbad_bbm(struct nand_chip *chip, loff_t ofs)
return nand_block_bad(chip, 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;
+ mutex_lock(&chip->lock);
+ if (chip->suspended) {
+ mutex_unlock(&chip->lock);
+ return -EBUSY;
}
- if (new_state == FL_PM_SUSPENDED) {
- if (chip->controller->active->state == FL_PM_SUSPENDED) {
- chip->state = FL_PM_SUSPENDED;
- spin_unlock(lock);
- return 0;
- }
- }
- 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 */
@@ -5017,6 +4997,8 @@ 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);
@@ -5716,9 +5698,6 @@ 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;
@@ -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;
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> --- drivers/mtd/nand/raw/nand_base.c | 111 +++++++++++++------------------ include/linux/mtd/rawnand.h | 24 +++---- 2 files changed, 54 insertions(+), 81 deletions(-)