On 03/03/2017 10:38 PM, Kamal Dasu wrote:
Marek,
On Sun, Feb 26, 2017 at 7:18 AM, Marek Vasut <marex@xxxxxxx> wrote:
On 02/24/2017 09:16 PM, Kamal Dasu wrote:
Added flash access synchronization methods spi_nor_get/release_device(). This
Should be get/put to be consistent with the rest of the kernel ...
Can change that.
change allows spi-nor driver to maintain flash states in spi-nor stucture for
read, write, erase, lock, unlock nor ops. Only when the flash state is FL_READY
a new state is set and spi-nor flash op is initiated. The state change is done
with a spin_lock held and released as soon as the state is changed. Else the
current process for spi-nor transfer is queued till the flash is in FL_READY
state. This change allows us to add mtd layer synchronization when the mtd
resume suspend handlers are added.
Signed-off-by: Kamal Dasu <kdasu.kdev@xxxxxxxxx>
---
drivers/mtd/spi-nor/spi-nor.c | 69 +++++++++++++++++++++++++++++++++++++++++++
include/linux/mtd/spi-nor.h | 4 +++
2 files changed, 73 insertions(+)
diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 8b71c11..5363807 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -89,6 +89,15 @@ struct flash_info {
#define JEDEC_MFR(info) ((info)->id[0])
+/* map table for spi_nor op to flashchip state */
+static int spi_nor_state[] = {
+ [SPI_NOR_OPS_READ] = FL_READING,
+ [SPI_NOR_OPS_WRITE] = FL_WRITING,
+ [SPI_NOR_OPS_ERASE] = FL_ERASING,
+ [SPI_NOR_OPS_LOCK] = FL_LOCKING,
+ [SPI_NOR_OPS_UNLOCK] = FL_UNLOCKING,
+};
Can't you just retain which instruction is in progress instead of adding
yet another orthogonal FL_FOO ?
I just used what other mtd flash drivers use. I could use the ops, but
will have to add the missing ops/states.
What is missing ?
static const struct flash_info *spi_nor_match_id(const char *name);
/*
@@ -396,10 +405,64 @@ static int erase_chip(struct spi_nor *nor)
return nor->write_reg(nor, SPINOR_OP_CHIP_ERASE, NULL, 0);
}
+/**
+ * spi_nor_get_device - [GENERIC] Get chip for selected access
+ * @param mtd MTD device structure
+ * @param new_state the state which is requested
+ *
+ * Get the nor flash device and lock it for exclusive access
+ */
+static int spi_nor_get_device(struct mtd_info *mtd, int new_state)
+{
+ struct spi_nor *nor = mtd_to_spi_nor(mtd);
+ DECLARE_WAITQUEUE(wait, current);
+
+ /*
+ * Grab the lock and see if the device is available
+ */
+ while (1) {
+ spin_lock(&nor->chip_lock);
+ if (nor->state == FL_READY) {
+ nor->state = new_state;
+ spin_unlock(&nor->chip_lock);
+ break;
+ }
+ if (new_state == FL_PM_SUSPENDED) {
+ spin_unlock(&nor->chip_lock);
+ return (nor->state == FL_PM_SUSPENDED) ? 0 : -EAGAIN;
+ }
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ add_wait_queue(&nor->wq, &wait);
+ spin_unlock(&nor->chip_lock);
+ schedule();
+ remove_wait_queue(&nor->wq, &wait);
Somehow, I have to wonder, doesn't runtime PM implement this sort of
functionality already ?
I did not see any API I could apply here.
Does runtime_pm_get()/runtime_pm_put() help here ?
[...]
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