mtd: spi-nor: introduce SPI 1-2-2 and SPI 1-4-4 protocols

This patch changes the prototype of spi_nor_scan(): its 3rd parameter
is replaced by a 'struct spi_nor_hwcaps' pointer, which tells the spi-nor
framework about the actual hardware capabilities supported by the SPI
controller and its driver.

Besides, this patch also introduces a new 'struct spi_nor_flash_parameter'
telling the spi-nor framework about the hardware capabilities supported by
the SPI flash memory and the associated settings required to use those
hardware caps.

Then, to improve the readability of spi_nor_scan(), the discovery of the
memory settings and the memory initialization are now split into two
dedicated functions.

1 - spi_nor_init_params()

The spi_nor_init_params() function is responsible for initializing the
'struct spi_nor_flash_parameter'. Currently this structure is filled with
legacy values but further patches will allow to override some parameter
values dynamically, for instance by reading the JESD216 Serial Flash
Discoverable Parameter (SFDP) tables from the SPI memory.
The spi_nor_init_params() function only deals with the hardware
capabilities of the SPI flash memory: especially it doesn't care about
the hardware capabilities supported by the SPI controller.

2 - spi_nor_setup()

The second function is called once the 'struct spi_nor_flash_parameter'
has been initialized by spi_nor_init_params().
With both 'struct spi_nor_flash_parameter' and 'struct spi_nor_hwcaps',
the new argument of spi_nor_scan(), spi_nor_setup() computes the best
match between hardware caps supported by both the (Q)SPI memory and
controller hence selecting the relevant settings for (Fast) Read and Page
Program operations.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Reviewed-by: Marek Vasut <marek.vasut@gmail.com>

1 files changed, 342 insertions, 98 deletions

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index dea8c9cbadf0..e653806070a1 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -150,24 +150,6 @@ static int read_cr(struct spi_nor *nor)
 }
 
 /*
- * Dummy Cycle calculation for different type of read.
- * It can be used to support more commands with
- * different dummy cycle requirements.
- */
-static inline int spi_nor_read_dummy_cycles(struct spi_nor *nor)
-{
-	switch (nor->flash_read) {
-	case SPI_NOR_FAST:
-	case SPI_NOR_DUAL:
-	case SPI_NOR_QUAD:
-		return 8;
-	case SPI_NOR_NORMAL:
-		return 0;
-	}
-	return 0;
-}
-
-/*
  * Write status register 1 byte
  * Returns negative if error occurred.
  */
@@ -1460,30 +1442,6 @@ static int spansion_quad_enable(struct spi_nor *nor)
 	return 0;
 }
 
-static int set_quad_mode(struct spi_nor *nor, const struct flash_info *info)
-{
-	int status;
-
-	switch (JEDEC_MFR(info)) {
-	case SNOR_MFR_MACRONIX:
-		status = macronix_quad_enable(nor);
-		if (status) {
-			dev_err(nor->dev, "Macronix quad-read not enabled\n");
-			return -EINVAL;
-		}
-		return status;
-	case SNOR_MFR_MICRON:
-		return 0;
-	default:
-		status = spansion_quad_enable(nor);
-		if (status) {
-			dev_err(nor->dev, "Spansion quad-read not enabled\n");
-			return -EINVAL;
-		}
-		return status;
-	}
-}
-
 static int spi_nor_check(struct spi_nor *nor)
 {
 	if (!nor->dev || !nor->read || !nor->write ||
@@ -1536,8 +1494,323 @@ static int s3an_nor_scan(const struct flash_info *info, struct spi_nor *nor)
 	return 0;
 }
 
-int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
+struct spi_nor_read_command {
+	u8			num_mode_clocks;
+	u8			num_wait_states;
+	u8			opcode;
+	enum spi_nor_protocol	proto;
+};
+
+struct spi_nor_pp_command {
+	u8			opcode;
+	enum spi_nor_protocol	proto;
+};
+
+enum spi_nor_read_command_index {
+	SNOR_CMD_READ,
+	SNOR_CMD_READ_FAST,
+
+	/* Dual SPI */
+	SNOR_CMD_READ_1_1_2,
+	SNOR_CMD_READ_1_2_2,
+	SNOR_CMD_READ_2_2_2,
+
+	/* Quad SPI */
+	SNOR_CMD_READ_1_1_4,
+	SNOR_CMD_READ_1_4_4,
+	SNOR_CMD_READ_4_4_4,
+
+	SNOR_CMD_READ_MAX
+};
+
+enum spi_nor_pp_command_index {
+	SNOR_CMD_PP,
+
+	/* Quad SPI */
+	SNOR_CMD_PP_1_1_4,
+	SNOR_CMD_PP_1_4_4,
+	SNOR_CMD_PP_4_4_4,
+
+	SNOR_CMD_PP_MAX
+};
+
+struct spi_nor_flash_parameter {
+	u64				size;
+	u32				page_size;
+
+	struct spi_nor_hwcaps		hwcaps;
+	struct spi_nor_read_command	reads[SNOR_CMD_READ_MAX];
+	struct spi_nor_pp_command	page_programs[SNOR_CMD_PP_MAX];
+
+	int (*quad_enable)(struct spi_nor *nor);
+};
+
+static void
+spi_nor_set_read_settings(struct spi_nor_read_command *read,
+			  u8 num_mode_clocks,
+			  u8 num_wait_states,
+			  u8 opcode,
+			  enum spi_nor_protocol proto)
+{
+	read->num_mode_clocks = num_mode_clocks;
+	read->num_wait_states = num_wait_states;
+	read->opcode = opcode;
+	read->proto = proto;
+}
+
+static void
+spi_nor_set_pp_settings(struct spi_nor_pp_command *pp,
+			u8 opcode,
+			enum spi_nor_protocol proto)
+{
+	pp->opcode = opcode;
+	pp->proto = proto;
+}
+
+static int spi_nor_init_params(struct spi_nor *nor,
+			       const struct flash_info *info,
+			       struct spi_nor_flash_parameter *params)
+{
+	/* Set legacy flash parameters as default. */
+	memset(params, 0, sizeof(*params));
+
+	/* Set SPI NOR sizes. */
+	params->size = info->sector_size * info->n_sectors;
+	params->page_size = info->page_size;
+
+	/* (Fast) Read settings. */
+	params->hwcaps.mask |= SNOR_HWCAPS_READ;
+	spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ],
+				  0, 0, SPINOR_OP_READ,
+				  SNOR_PROTO_1_1_1);
+
+	if (!(info->flags & SPI_NOR_NO_FR)) {
+		params->hwcaps.mask |= SNOR_HWCAPS_READ_FAST;
+		spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ_FAST],
+					  0, 8, SPINOR_OP_READ_FAST,
+					  SNOR_PROTO_1_1_1);
+	}
+
+	if (info->flags & SPI_NOR_DUAL_READ) {
+		params->hwcaps.mask |= SNOR_HWCAPS_READ_1_1_2;
+		spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ_1_1_2],
+					  0, 8, SPINOR_OP_READ_1_1_2,
+					  SNOR_PROTO_1_1_2);
+	}
+
+	if (info->flags & SPI_NOR_QUAD_READ) {
+		params->hwcaps.mask |= SNOR_HWCAPS_READ_1_1_4;
+		spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ_1_1_4],
+					  0, 8, SPINOR_OP_READ_1_1_4,
+					  SNOR_PROTO_1_1_4);
+	}
+
+	/* Page Program settings. */
+	params->hwcaps.mask |= SNOR_HWCAPS_PP;
+	spi_nor_set_pp_settings(&params->page_programs[SNOR_CMD_PP],
+				SPINOR_OP_PP, SNOR_PROTO_1_1_1);
+
+	/* Select the procedure to set the Quad Enable bit. */
+	if (params->hwcaps.mask & (SNOR_HWCAPS_READ_QUAD |
+				   SNOR_HWCAPS_PP_QUAD)) {
+		switch (JEDEC_MFR(info)) {
+		case SNOR_MFR_MACRONIX:
+			params->quad_enable = macronix_quad_enable;
+			break;
+
+		case SNOR_MFR_MICRON:
+			break;
+
+		default:
+			params->quad_enable = spansion_quad_enable;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static int spi_nor_hwcaps2cmd(u32 hwcaps, const int table[][2], size_t size)
+{
+	size_t i;
+
+	for (i = 0; i < size; i++)
+		if (table[i][0] == (int)hwcaps)
+			return table[i][1];
+
+	return -EINVAL;
+}
+
+static int spi_nor_hwcaps_read2cmd(u32 hwcaps)
+{
+	static const int hwcaps_read2cmd[][2] = {
+		{ SNOR_HWCAPS_READ,		SNOR_CMD_READ },
+		{ SNOR_HWCAPS_READ_FAST,	SNOR_CMD_READ_FAST },
+		{ SNOR_HWCAPS_READ_1_1_2,	SNOR_CMD_READ_1_1_2 },
+		{ SNOR_HWCAPS_READ_1_2_2,	SNOR_CMD_READ_1_2_2 },
+		{ SNOR_HWCAPS_READ_2_2_2,	SNOR_CMD_READ_2_2_2 },
+		{ SNOR_HWCAPS_READ_1_1_4,	SNOR_CMD_READ_1_1_4 },
+		{ SNOR_HWCAPS_READ_1_4_4,	SNOR_CMD_READ_1_4_4 },
+		{ SNOR_HWCAPS_READ_4_4_4,	SNOR_CMD_READ_4_4_4 },
+	};
+
+	return spi_nor_hwcaps2cmd(hwcaps, hwcaps_read2cmd,
+				  ARRAY_SIZE(hwcaps_read2cmd));
+}
+
+static int spi_nor_hwcaps_pp2cmd(u32 hwcaps)
+{
+	static const int hwcaps_pp2cmd[][2] = {
+		{ SNOR_HWCAPS_PP,		SNOR_CMD_PP },
+		{ SNOR_HWCAPS_PP_1_1_4,		SNOR_CMD_PP_1_1_4 },
+		{ SNOR_HWCAPS_PP_1_4_4,		SNOR_CMD_PP_1_4_4 },
+		{ SNOR_HWCAPS_PP_4_4_4,		SNOR_CMD_PP_4_4_4 },
+	};
+
+	return spi_nor_hwcaps2cmd(hwcaps, hwcaps_pp2cmd,
+				  ARRAY_SIZE(hwcaps_pp2cmd));
+}
+
+static int spi_nor_select_read(struct spi_nor *nor,
+			       const struct spi_nor_flash_parameter *params,
+			       u32 shared_hwcaps)
+{
+	int cmd, best_match = fls(shared_hwcaps & SNOR_HWCAPS_READ_MASK) - 1;
+	const struct spi_nor_read_command *read;
+
+	if (best_match < 0)
+		return -EINVAL;
+
+	cmd = spi_nor_hwcaps_read2cmd(BIT(best_match));
+	if (cmd < 0)
+		return -EINVAL;
+
+	read = &params->reads[cmd];
+	nor->read_opcode = read->opcode;
+	nor->read_proto = read->proto;
+
+	/*
+	 * In the spi-nor framework, we don't need to make the difference
+	 * between mode clock cycles and wait state clock cycles.
+	 * Indeed, the value of the mode clock cycles is used by a QSPI
+	 * flash memory to know whether it should enter or leave its 0-4-4
+	 * (Continuous Read / XIP) mode.
+	 * eXecution In Place is out of the scope of the mtd sub-system.
+	 * Hence we choose to merge both mode and wait state clock cycles
+	 * into the so called dummy clock cycles.
+	 */
+	nor->read_dummy = read->num_mode_clocks + read->num_wait_states;
+	return 0;
+}
+
+static int spi_nor_select_pp(struct spi_nor *nor,
+			     const struct spi_nor_flash_parameter *params,
+			     u32 shared_hwcaps)
+{
+	int cmd, best_match = fls(shared_hwcaps & SNOR_HWCAPS_PP_MASK) - 1;
+	const struct spi_nor_pp_command *pp;
+
+	if (best_match < 0)
+		return -EINVAL;
+
+	cmd = spi_nor_hwcaps_pp2cmd(BIT(best_match));
+	if (cmd < 0)
+		return -EINVAL;
+
+	pp = &params->page_programs[cmd];
+	nor->program_opcode = pp->opcode;
+	nor->write_proto = pp->proto;
+	return 0;
+}
+
+static int spi_nor_select_erase(struct spi_nor *nor,
+				const struct flash_info *info)
+{
+	struct mtd_info *mtd = &nor->mtd;
+
+#ifdef CONFIG_MTD_SPI_NOR_USE_4K_SECTORS
+	/* prefer "small sector" erase if possible */
+	if (info->flags & SECT_4K) {
+		nor->erase_opcode = SPINOR_OP_BE_4K;
+		mtd->erasesize = 4096;
+	} else if (info->flags & SECT_4K_PMC) {
+		nor->erase_opcode = SPINOR_OP_BE_4K_PMC;
+		mtd->erasesize = 4096;
+	} else
+#endif
+	{
+		nor->erase_opcode = SPINOR_OP_SE;
+		mtd->erasesize = info->sector_size;
+	}
+	return 0;
+}
+
+static int spi_nor_setup(struct spi_nor *nor, const struct flash_info *info,
+			 const struct spi_nor_flash_parameter *params,
+			 const struct spi_nor_hwcaps *hwcaps)
+{
+	u32 ignored_mask, shared_mask;
+	bool enable_quad_io;
+	int err;
+
+	/*
+	 * Keep only the hardware capabilities supported by both the SPI
+	 * controller and the SPI flash memory.
+	 */
+	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_PP_4_4_4);
+	if (shared_mask & ignored_mask) {
+		dev_dbg(nor->dev,
+			"SPI n-n-n protocols are not supported yet.\n");
+		shared_mask &= ~ignored_mask;
+	}
+
+	/* Select the (Fast) Read command. */
+	err = spi_nor_select_read(nor, params, shared_mask);
+	if (err) {
+		dev_err(nor->dev,
+			"can't select read settings supported by both the SPI controller and memory.\n");
+		return err;
+	}
+
+	/* Select the Page Program command. */
+	err = spi_nor_select_pp(nor, params, shared_mask);
+	if (err) {
+		dev_err(nor->dev,
+			"can't select write settings supported by both the SPI controller and memory.\n");
+		return err;
+	}
+
+	/* Select the Sector Erase command. */
+	err = spi_nor_select_erase(nor, info);
+	if (err) {
+		dev_err(nor->dev,
+			"can't select erase settings supported by both the SPI controller and memory.\n");
+		return err;
+	}
+
+	/* Enable Quad I/O if needed. */
+	enable_quad_io = (spi_nor_get_protocol_width(nor->read_proto) == 4 ||
+			  spi_nor_get_protocol_width(nor->write_proto) == 4);
+	if (enable_quad_io && params->quad_enable) {
+		err = params->quad_enable(nor);
+		if (err) {
+			dev_err(nor->dev, "quad mode not supported\n");
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+int spi_nor_scan(struct spi_nor *nor, const char *name,
+		 const struct spi_nor_hwcaps *hwcaps)
 {
+	struct spi_nor_flash_parameter params;
 	const struct flash_info *info = NULL;
 	struct device *dev = nor->dev;
 	struct mtd_info *mtd = &nor->mtd;
@@ -1549,6 +1822,11 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 	if (ret)
 		return ret;
 
+	/* Reset SPI protocol for all commands. */
+	nor->reg_proto = SNOR_PROTO_1_1_1;
+	nor->read_proto = SNOR_PROTO_1_1_1;
+	nor->write_proto = SNOR_PROTO_1_1_1;
+
 	if (name)
 		info = spi_nor_match_id(name);
 	/* Try to auto-detect if chip name wasn't specified or not found */
@@ -1591,6 +1869,11 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 	if (info->flags & SPI_S3AN)
 		nor->flags |=  SNOR_F_READY_XSR_RDY;
 
+	/* Parse the Serial Flash Discoverable Parameters table. */
+	ret = spi_nor_init_params(nor, info, &params);
+	if (ret)
+		return ret;
+
 	/*
 	 * Atmel, SST, Intel/Numonyx, and others serial NOR tend to power up
 	 * with the software protection bits set
@@ -1611,7 +1894,7 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 	mtd->type = MTD_NORFLASH;
 	mtd->writesize = 1;
 	mtd->flags = MTD_CAP_NORFLASH;
-	mtd->size = info->sector_size * info->n_sectors;
+	mtd->size = params.size;
 	mtd->_erase = spi_nor_erase;
 	mtd->_read = spi_nor_read;
 
@@ -1642,75 +1925,38 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 	if (info->flags & NO_CHIP_ERASE)
 		nor->flags |= SNOR_F_NO_OP_CHIP_ERASE;
 
-#ifdef CONFIG_MTD_SPI_NOR_USE_4K_SECTORS
-	/* prefer "small sector" erase if possible */
-	if (info->flags & SECT_4K) {
-		nor->erase_opcode = SPINOR_OP_BE_4K;
-		mtd->erasesize = 4096;
-	} else if (info->flags & SECT_4K_PMC) {
-		nor->erase_opcode = SPINOR_OP_BE_4K_PMC;
-		mtd->erasesize = 4096;
-	} else
-#endif
-	{
-		nor->erase_opcode = SPINOR_OP_SE;
-		mtd->erasesize = info->sector_size;
-	}
-
 	if (info->flags & SPI_NOR_NO_ERASE)
 		mtd->flags |= MTD_NO_ERASE;
 
 	mtd->dev.parent = dev;
-	nor->page_size = info->page_size;
+	nor->page_size = params.page_size;
 	mtd->writebufsize = nor->page_size;
 
 	if (np) {
 		/* If we were instantiated by DT, use it */
 		if (of_property_read_bool(np, "m25p,fast-read"))
-			nor->flash_read = SPI_NOR_FAST;
+			params.hwcaps.mask |= SNOR_HWCAPS_READ_FAST;
 		else
-			nor->flash_read = SPI_NOR_NORMAL;
+			params.hwcaps.mask &= ~SNOR_HWCAPS_READ_FAST;
 	} else {
 		/* If we weren't instantiated by DT, default to fast-read */
-		nor->flash_read = SPI_NOR_FAST;
+		params.hwcaps.mask |= SNOR_HWCAPS_READ_FAST;
 	}
 
 	/* Some devices cannot do fast-read, no matter what DT tells us */
 	if (info->flags & SPI_NOR_NO_FR)
-		nor->flash_read = SPI_NOR_NORMAL;
-
-	/* Quad/Dual-read mode takes precedence over fast/normal */
-	if (mode == SPI_NOR_QUAD && info->flags & SPI_NOR_QUAD_READ) {
-		ret = set_quad_mode(nor, info);
-		if (ret) {
-			dev_err(dev, "quad mode not supported\n");
-			return ret;
-		}
-		nor->flash_read = SPI_NOR_QUAD;
-	} else if (mode == SPI_NOR_DUAL && info->flags & SPI_NOR_DUAL_READ) {
-		nor->flash_read = SPI_NOR_DUAL;
-	}
-
-	/* Default commands */
-	switch (nor->flash_read) {
-	case SPI_NOR_QUAD:
-		nor->read_opcode = SPINOR_OP_READ_1_1_4;
-		break;
-	case SPI_NOR_DUAL:
-		nor->read_opcode = SPINOR_OP_READ_1_1_2;
-		break;
-	case SPI_NOR_FAST:
-		nor->read_opcode = SPINOR_OP_READ_FAST;
-		break;
-	case SPI_NOR_NORMAL:
-		nor->read_opcode = SPINOR_OP_READ;
-		break;
-	default:
-		dev_err(dev, "No Read opcode defined\n");
-		return -EINVAL;
-	}
+		params.hwcaps.mask &= ~SNOR_HWCAPS_READ_FAST;
 
-	nor->program_opcode = SPINOR_OP_PP;
+	/*
+	 * Configure the SPI memory:
+	 * - select op codes for (Fast) Read, Page Program and Sector Erase.
+	 * - set the number of dummy cycles (mode cycles + wait states).
+	 * - set the SPI protocols for register and memory accesses.
+	 * - set the Quad Enable bit if needed (required by SPI x-y-4 protos).
+	 */
+	ret = spi_nor_setup(nor, info, &params, hwcaps);
+	if (ret)
+		return ret;
 
 	if (info->addr_width)
 		nor->addr_width = info->addr_width;
@@ -1732,8 +1978,6 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 		return -EINVAL;
 	}
 
-	nor->read_dummy = spi_nor_read_dummy_cycles(nor);
-
 	if (info->flags & SPI_S3AN) {
 		ret = s3an_nor_scan(info, nor);
 		if (ret)