The spi-nor framework currently expects all Fast Read operations to use 8
dummy clock cycles. Especially some drivers like m25p80 can only support
multiple of 8 dummy clock cycles.
On Macronix memories, the number of dummy clock cycles to be used by Fast
Read commands can be safely set to 8 by updating the DC0 and DC1 volatile
bits inside the Configuration Register.
According to the mx66l1g45g datasheet from Macronix, using 8 dummy clock
cycles should be enough to set the SPI bus clock frequency up to:
- 133 MHz for Fast Read 1-1-1, 1-1-2, 1-1-4 and 1-2-2 commands in Single
Transfer Rate (STR)
- 104 MHz for Fast Read 1-4-4 (or 4-4-4 in QPI mode) commands (STR)
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>
---
drivers/mtd/spi-nor/spi-nor.c | 155 +++++++++++++++++++++++++++++++++++++++---
1 file changed, 147 insertions(+), 8 deletions(-)
diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 3f79619aea52..68abae5c72e9 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -1190,6 +1190,136 @@ static int winbond_quad_enable(struct spi_nor *nor)
return 0;
}
+static int macronix_dummy2code(u8 read_opcode, u8 read_dummy, u8 *dc)
+{
+ switch (read_opcode) {
+ case SPINOR_OP_READ:
+ case SPINOR_OP_READ4:
+ *dc = 0;
+ break;
+
+ case SPINOR_OP_READ_FAST:
+ case SPINOR_OP_READ_1_1_2:
+ case SPINOR_OP_READ_1_1_4:
+ case SPINOR_OP_READ4_FAST:
+ case SPINOR_OP_READ4_1_1_2:
+ case SPINOR_OP_READ4_1_1_4:
+ switch (read_dummy) {
+ case 6:
+ *dc = 1;
+ break;
+ case 8:
+ *dc = 0;
+ break;
+ case 10:
+ *dc = 3;
+ break;
+ default:
+ return -EINVAL;
+ }
+ break;
+
+ case SPINOR_OP_READ_1_2_2:
+ case SPINOR_OP_READ4_1_2_2:
+ switch (read_dummy) {
+ case 4:
+ *dc = 0;
+ break;
+ case 6:
+ *dc = 1;
+ break;
+ case 8:
+ *dc = 2;
+ break;
+ case 10:
+ *dc = 3;
+ default:
+ return -EINVAL;
+ }
+ break;
+
+ case SPINOR_OP_READ_1_4_4:
+ case SPINOR_OP_READ4_1_4_4:
+ switch (read_dummy) {
+ case 4:
+ *dc = 1;
+ break;
+ case 6:
+ *dc = 0;
+ break;
+ case 8:
+ *dc = 2;
+ break;
+ case 10:
+ *dc = 3;
+ default:
+ return -EINVAL;
+ }
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int macronix_set_dummy_cycles(struct spi_nor *nor, u8 read_dummy)
+{
+ int ret, sr, cr, mask, val;
+ u16 sr_cr;
+ u8 dc;
+
+ /* Convert the number of dummy cycles into Macronix DC volatile bits */
+ ret = macronix_dummy2code(nor->read_opcode, read_dummy, &dc);
+ if (ret)
+ return ret;
+
+ mask = GENMASK(7, 6);
+ val = (dc << 6) & mask;
+
+ cr = read_cr(nor);
+ if (cr < 0) {
+ dev_err(nor->dev, "error while reading the config register\n");
+ return cr;
+ }
+
+ if ((cr & mask) == val) {
+ nor->read_dummy = read_dummy;
+ return 0;
+ }
+
+ sr = read_sr(nor);
+ if (sr < 0) {
+ dev_err(nor->dev, "error while reading the status register\n");
+ return sr;
+ }
+
+ cr = (cr & ~mask) | val;
+ sr_cr = (sr & 0xff) | ((cr & 0xff) << 8);
+ write_enable(nor);
+ ret = write_sr_cr(nor, sr_cr);
+ if (ret) {
+ dev_err(nor->dev,
+ "error while writing the SR and CR registers\n");
+ return ret;
+ }
+
+ ret = spi_nor_wait_till_ready(nor);
+ if (ret)
+ return ret;
+
+ cr = read_cr(nor);
+ if (cr < 0 || (cr & mask) != val) {
+ dev_err(nor->dev, "Macronix Dummy Cycle bits not updated\n");
+ return -EINVAL;
+ }
+
+ /* Save the number of dummy cycles to use with Fast Read commands */
+ nor->read_dummy = read_dummy;
+ return 0;
+}
+
static int macronix_set_quad_mode(struct spi_nor *nor)
{
int status;
@@ -1207,8 +1337,7 @@ static int macronix_set_quad_mode(struct spi_nor *nor)
* read (performance enhance) mode by mistake!
*/
nor->read_opcode = SPINOR_OP_READ_1_4_4;
- nor->read_dummy = 8;
- return 0;
+ return macronix_set_dummy_cycles(nor, 8);
}
/*
@@ -1221,6 +1350,9 @@ static int macronix_set_quad_mode(struct spi_nor *nor)
* entering the continuous read mode by mistake if some
* performance enhance toggling bits P0-P7 were written during
* dummy/mode cycles.
+ *
+ * Use the Fast Read Quad Output 1-1-4 (0x6b) command with 8 dummy
+ * cycles (up to 133MHz for STR and 66MHz for DTR).
*/
status = macronix_quad_enable(nor);
if (status) {
@@ -1229,8 +1361,7 @@ static int macronix_set_quad_mode(struct spi_nor *nor)
}
nor->read_proto = SNOR_PROTO_1_1_4;
nor->read_opcode = SPINOR_OP_READ_1_1_4;
- nor->read_dummy = 8;
- return 0;
+ return macronix_set_dummy_cycles(nor, 8);
}
/*
@@ -1241,16 +1372,25 @@ static int macronix_set_quad_mode(struct spi_nor *nor)
static int macronix_set_dual_mode(struct spi_nor *nor)
{
+ /*
+ * Use the Fast Read Dual Output 1-1-2 (0x3b) command with 8 dummy
+ * cycles (up to 133MHz for STR and 66MHz for DTR).
+ */
nor->read_proto = SNOR_PROTO_1_1_2;
nor->read_opcode = SPINOR_OP_READ_1_1_2;
- nor->read_dummy = 8;
- return 0;
+ return macronix_set_dummy_cycles(nor, 8);
}
static int macronix_set_single_mode(struct spi_nor *nor)
{
u8 read_dummy;
+ /*
+ * Configure 8 dummy cycles for Fast Read 1-1-1 (0x0b) command (up to
+ * 133MHz for STR and 66MHz for DTR). The Read 1-1-1 (0x03) command
+ * expects no dummy cycle.
+ * read_opcode should not be overridden here!
+ */
switch (nor->read_opcode) {
case SPINOR_OP_READ:
case SPINOR_OP_READ4:
@@ -1263,8 +1403,7 @@ static int macronix_set_single_mode(struct spi_nor *nor)
}
nor->read_proto = SNOR_PROTO_1_1_1;
- nor->read_dummy = read_dummy;
- return 0;
+ return macronix_set_dummy_cycles(nor, read_dummy);
}
static int winbond_set_quad_mode(struct spi_nor *nor)
--
1.8.2.2
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
