From: Boris Brezillon <boris.brezil...@bootlin.com>

The spi-mem layer provides a spi_mem_supports_op() function to check
whether a specific operation is supported by the controller or not.
This is much more accurate than the hwcaps selection logic based on
SPI_{RX,TX}_ flags.

Rework the hwcaps selection logic to use spi_mem_supports_op() when
nor->spimem != NULL.

Signed-off-by: Boris Brezillon <boris.brezil...@bootlin.com>
Signed-off-by: Vignesh Raghavendra <vigne...@ti.com>
---
Chagnes wrt RFC:
Fix checkpatch issues
Rebase onto latest

 drivers/mtd/spi-nor/spi-nor.c | 164 ++++++++++++++++++++++++++--------
 include/linux/mtd/spi-nor.h   |  14 +++
 2 files changed, 142 insertions(+), 36 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 03c8c346c9ae..d48ae3c9661d 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -2852,6 +2852,110 @@ static int spi_nor_read_sfdp(struct spi_nor *nor, u32 
addr,
        return ret;
 }
 
+static int spi_nor_spimem_check_readop(struct spi_nor *nor,
+                                      const struct spi_nor_read_command *read)
+{
+       struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(read->opcode, 1),
+                                         SPI_MEM_OP_ADDR(3, 0, 1),
+                                         SPI_MEM_OP_DUMMY(0, 1),
+                                         SPI_MEM_OP_DATA_IN(0, NULL, 1));
+
+       op.cmd.buswidth = spi_nor_get_protocol_inst_nbits(read->proto);
+       op.addr.buswidth = spi_nor_get_protocol_addr_nbits(read->proto);
+       op.data.buswidth = spi_nor_get_protocol_data_nbits(read->proto);
+       op.dummy.buswidth = op.addr.buswidth;
+       op.dummy.nbytes = (read->num_mode_clocks + read->num_wait_states) *
+                         op.dummy.buswidth / 8;
+
+       /*
+        * First test with 3 address bytes. The opcode itself might already
+        * be a 4B addressing opcode but we don't care, because SPI controller
+        * implementation should not check the opcode, but just the sequence.
+        */
+       if (!spi_mem_supports_op(nor->spimem, &op))
+               return -ENOTSUPP;
+
+       /* Now test with 4 address bytes. */
+       op.addr.nbytes = 4;
+       if (!spi_mem_supports_op(nor->spimem, &op))
+               return -ENOTSUPP;
+
+       return 0;
+}
+
+static int spi_nor_spimem_check_progop(struct spi_nor *nor,
+                                      const struct spi_nor_pp_command *pp)
+{
+       struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(pp->opcode, 1),
+                                         SPI_MEM_OP_ADDR(3, 0, 1),
+                                         SPI_MEM_OP_NO_DUMMY,
+                                         SPI_MEM_OP_DATA_OUT(0, NULL, 1));
+
+       op.cmd.buswidth = spi_nor_get_protocol_inst_nbits(pp->proto);
+       op.addr.buswidth = spi_nor_get_protocol_addr_nbits(pp->proto);
+       op.data.buswidth = spi_nor_get_protocol_data_nbits(pp->proto);
+
+       /*
+        * First test with 3 address bytes. The opcode itself might already
+        * be a 4B addressing opcode but we don't care, because SPI controller
+        * implementation should not check the opcode, but just the sequence.
+        */
+       if (!spi_mem_supports_op(nor->spimem, &op))
+               return -ENOTSUPP;
+
+       /* Now test with 4 address bytes. */
+       op.addr.nbytes = 4;
+       if (!spi_mem_supports_op(nor->spimem, &op))
+               return -ENOTSUPP;
+
+       return 0;
+}
+
+static void
+spi_nor_spimem_adjust_hwcaps(struct spi_nor *nor,
+                            const struct spi_nor_flash_parameter *params,
+                            u32 *hwcaps)
+{
+       unsigned int cap;
+
+       /* DTR modes are not supported yet, mask them all. */
+       *hwcaps &= ~SNOR_HWCAPS_DTR;
+
+       /* X-X-X modes are not supported yet, mask them all. */
+       *hwcaps &= ~SNOR_HWCAPS_X_X_X;
+
+       /* Start with read commands. */
+       for (cap = 0; cap < 32; cap++) {
+               int idx;
+
+               if (!(*hwcaps & BIT(cap)))
+                       continue;
+
+               idx = spi_nor_hwcaps_read2cmd(BIT(cap));
+               if (idx < 0)
+                       continue;
+
+               if (spi_nor_spimem_check_readop(nor, &params->reads[idx]))
+                       *hwcaps &= ~BIT(cap);
+       }
+
+       /* Now check program commands. */
+       for (cap = 0; cap < 32; cap++) {
+               int idx;
+
+               if (!(*hwcaps & BIT(cap)))
+                       continue;
+
+               idx = spi_nor_hwcaps_pp2cmd(BIT(cap));
+               if (idx < 0)
+                       continue;
+
+               if (spi_nor_spimem_check_progop(nor,
+                                               &params->page_programs[idx]))
+                       *hwcaps &= ~BIT(cap);
+       }
+}
+
 /**
  * spi_nor_read_sfdp_dma_unsafe() - read Serial Flash Discoverable Parameters.
  * @nor:       pointer to a 'struct spi_nor'
@@ -4259,16 +4363,25 @@ static int spi_nor_setup(struct spi_nor *nor,
         */
        shared_mask = hwcaps->mask & params->hwcaps.mask;
 
-       /* SPI n-n-n protocols are not supported yet. */
-       ignored_mask = (SNOR_HWCAPS_READ_2_2_2 |
-                       SNOR_HWCAPS_READ_4_4_4 |
-                       SNOR_HWCAPS_READ_8_8_8 |
-                       SNOR_HWCAPS_PP_4_4_4 |
-                       SNOR_HWCAPS_PP_8_8_8);
-       if (shared_mask & ignored_mask) {
-               dev_dbg(nor->dev,
-                       "SPI n-n-n protocols are not supported yet.\n");
-               shared_mask &= ~ignored_mask;
+       if (nor->spimem) {
+               /*
+                * When called from spi_nor_probe(), all caps are set and we
+                * need to discard some of them based on what the SPI
+                * controller actually supports (using spi_mem_supports_op()).
+                */
+               spi_nor_spimem_adjust_hwcaps(nor, params, &shared_mask);
+       } else {
+               /*
+                * SPI n-n-n protocols are not supported when the SPI
+                * controller directly implements the spi_nor interface.
+                * Yet another reason to switch to spi-mem.
+                */
+               ignored_mask = SNOR_HWCAPS_X_X_X;
+               if (shared_mask & ignored_mask) {
+                       dev_dbg(nor->dev,
+                               "SPI n-n-n protocols are not supported.\n");
+                       shared_mask &= ~ignored_mask;
+               }
        }
 
        /* Select the (Fast) Read command. */
@@ -4591,11 +4704,11 @@ static int spi_nor_probe(struct spi_mem *spimem)
        struct spi_device *spi = spimem->spi;
        struct flash_platform_data *data;
        struct spi_nor *nor;
-       struct spi_nor_hwcaps hwcaps = {
-               .mask = SNOR_HWCAPS_READ |
-                       SNOR_HWCAPS_READ_FAST |
-                       SNOR_HWCAPS_PP,
-       };
+       /*
+        * Enable all caps by default. The core will mask them after
+        * checking what's really supported using spi_mem_supports_op().
+        */
+       struct spi_nor_hwcaps hwcaps = { .mask = SNOR_HWCAPS_ALL };
        char *flash_name;
        int ret;
 
@@ -4624,27 +4737,6 @@ static int spi_nor_probe(struct spi_mem *spimem)
 
        spi_mem_set_drvdata(spimem, nor);
 
-       if (spi->mode & SPI_RX_OCTAL) {
-               hwcaps.mask |= SNOR_HWCAPS_READ_1_1_8;
-
-               if (spi->mode & SPI_TX_OCTAL)
-                       hwcaps.mask |= (SNOR_HWCAPS_READ_1_8_8 |
-                                       SNOR_HWCAPS_PP_1_1_8 |
-                                       SNOR_HWCAPS_PP_1_8_8);
-       } else if (spi->mode & SPI_RX_QUAD) {
-               hwcaps.mask |= SNOR_HWCAPS_READ_1_1_4;
-
-               if (spi->mode & SPI_TX_QUAD)
-                       hwcaps.mask |= (SNOR_HWCAPS_READ_1_4_4 |
-                                       SNOR_HWCAPS_PP_1_1_4 |
-                                       SNOR_HWCAPS_PP_1_4_4);
-       } else if (spi->mode & SPI_RX_DUAL) {
-               hwcaps.mask |= SNOR_HWCAPS_READ_1_1_2;
-
-               if (spi->mode & SPI_TX_DUAL)
-                       hwcaps.mask |= SNOR_HWCAPS_READ_1_2_2;
-       }
-
        if (data && data->name)
                nor->mtd.name = data->name;
 
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index ac16745f5ef8..1d56c437f553 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -523,6 +523,20 @@ struct spi_nor_hwcaps {
 #define SNOR_HWCAPS_PP_1_8_8   BIT(21)
 #define SNOR_HWCAPS_PP_8_8_8   BIT(22)
 
+#define SNOR_HWCAPS_X_X_X      (SNOR_HWCAPS_READ_2_2_2 |       \
+                                SNOR_HWCAPS_READ_4_4_4 |       \
+                                SNOR_HWCAPS_READ_8_8_8 |       \
+                                SNOR_HWCAPS_PP_4_4_4 |         \
+                                SNOR_HWCAPS_PP_8_8_8)
+
+#define SNOR_HWCAPS_DTR                (SNOR_HWCAPS_READ_1_1_1_DTR |   \
+                                SNOR_HWCAPS_READ_1_2_2_DTR |   \
+                                SNOR_HWCAPS_READ_1_4_4_DTR |   \
+                                SNOR_HWCAPS_READ_1_8_8_DTR)
+
+#define SNOR_HWCAPS_ALL                (SNOR_HWCAPS_READ_MASK |        \
+                                SNOR_HWCAPS_PP_MASK)
+
 /**
  * spi_nor_scan() - scan the SPI NOR
  * @nor:       the spi_nor structure
-- 
2.21.0

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