mtd: nand: automate NAND timings selection

The NAND framework provides several helpers to query timing modes supported
by a NAND chip, but this implies that all NAND controller drivers have
to implement the same timings selection dance. Also currently NAND
devices can be resetted at arbitrary places which also resets the timing
for ONFI chips to timing mode 0.

Provide a common logic to select the best timings based on ONFI or
->onfi_timing_mode_default information. Hook this into nand_reset()
to make sure the new timing is applied each time during a reset.

NAND controller willing to support timings adjustment should just
implement the ->setup_data_interface() method.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 10 insertions, 4 deletions

diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 0c9412c2d80b..d3e3f8d03336 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -751,10 +751,9 @@ nand_get_sdr_timings(const struct nand_data_interface *conf)
  *                      also from the datasheet. It is the recommended ECC step
  *                      size, if known; if unknown, set to zero.
  * @onfi_timing_mode_default: [INTERN] default ONFI timing mode. This field is
- *                            either deduced from the datasheet if the NAND
- *                            chip is not ONFI compliant or set to 0 if it is
- *                            (an ONFI chip is always configured in mode 0
- *                            after a NAND reset)
+ *                            set to the actually used ONFI mode if the chip is
+ *                            ONFI compliant or deduced from the datasheet if
+ *                            the NAND chip is not ONFI compliant.
  * @numchips:           [INTERN] number of physical chips
  * @chipsize:           [INTERN] the size of one chip for multichip arrays
  * @pagemask:           [INTERN] page number mask = number of (pages / chip) - 1
@@ -774,6 +773,7 @@ nand_get_sdr_timings(const struct nand_data_interface *conf)
  * @read_retries:       [INTERN] the number of read retry modes supported
  * @onfi_set_features:  [REPLACEABLE] set the features for ONFI nand
  * @onfi_get_features:  [REPLACEABLE] get the features for ONFI nand
+ * @setup_data_interface: [OPTIONAL] setup the data interface and timing
  * @bbt:                [INTERN] bad block table pointer
  * @bbt_td:             [REPLACEABLE] bad block table descriptor for flash
  *                      lookup.
@@ -820,6 +820,10 @@ struct nand_chip {
         int (*onfi_get_features)(struct mtd_info *mtd, struct nand_chip *chip,
                         int feature_addr, uint8_t *subfeature_para);
         int (*setup_read_retry)(struct mtd_info *mtd, int retry_mode);
+        int (*setup_data_interface)(struct mtd_info *mtd,
+                                    const struct nand_data_interface *conf,
+                                    bool check_only);
+
 
         int chip_delay;
         unsigned int options;
@@ -849,6 +853,8 @@ struct nand_chip {
                 struct nand_jedec_params jedec_params;
         };
 
+        struct nand_data_interface *data_interface;
+
         int read_retries;
 
         flstate_t state;