mtd: nand: Introduce nand_data_interface

Currently we have no data structure to fully describe a NAND timing.
We only have struct nand_sdr_timings for NAND timings in SDR mode,
but nothing for DDR mode and also no container to store both types
of timing.
This patch adds struct nand_data_interface which stores the timing
type and a union of different timings. This can be used to pass to
drivers in order to configure the timing.
Add kerneldoc for struct nand_sdr_timings while touching it anyway.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
[Linux commit: eee64b700e26b9bcc6fce024681c31f5e12271fc]
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

include/linux/mtd/nand.h

@@ -585,6 +585,123 @@ struct nand_buffers {
 };
 
 /**
+ * struct nand_sdr_timings - SDR NAND chip timings
+ *
+ * This struct defines the timing requirements of a SDR NAND chip.
+ * These information can be found in every NAND datasheets and the timings
+ * meaning are described in the ONFI specifications:
+ * www.onfi.org/~/media/ONFI/specs/onfi_3_1_spec.pdf (chapter 4.15 Timing
+ * Parameters)
+ *
+ * All these timings are expressed in picoseconds.
+ *
+ * @tALH_min: ALE hold time
+ * @tADL_min: ALE to data loading time
+ * @tALS_min: ALE setup time
+ * @tAR_min: ALE to RE# delay
+ * @tCEA_max: CE# access time
+ * @tCEH_min: CE# high hold time
+ * @tCH_min:  CE# hold time
+ * @tCHZ_max: CE# high to output hi-Z
+ * @tCLH_min: CLE hold time
+ * @tCLR_min: CLE to RE# delay
+ * @tCLS_min: CLE setup time
+ * @tCOH_min: CE# high to output hold
+ * @tCS_min: CE# setup time
+ * @tDH_min: Data hold time
+ * @tDS_min: Data setup time
+ * @tFEAT_max: Busy time for Set Features and Get Features
+ * @tIR_min: Output hi-Z to RE# low
+ * @tITC_max: Interface and Timing Mode Change time
+ * @tRC_min: RE# cycle time
+ * @tREA_max: RE# access time
+ * @tREH_min: RE# high hold time
+ * @tRHOH_min: RE# high to output hold
+ * @tRHW_min: RE# high to WE# low
+ * @tRHZ_max: RE# high to output hi-Z
+ * @tRLOH_min: RE# low to output hold
+ * @tRP_min: RE# pulse width
+ * @tRR_min: Ready to RE# low (data only)
+ * @tRST_max: Device reset time, measured from the falling edge of R/B# to the
+ *	      rising edge of R/B#.
+ * @tWB_max: WE# high to SR[6] low
+ * @tWC_min: WE# cycle time
+ * @tWH_min: WE# high hold time
+ * @tWHR_min: WE# high to RE# low
+ * @tWP_min: WE# pulse width
+ * @tWW_min: WP# transition to WE# low
+ */
+struct nand_sdr_timings {
+	u32 tALH_min;
+	u32 tADL_min;
+	u32 tALS_min;
+	u32 tAR_min;
+	u32 tCEA_max;
+	u32 tCEH_min;
+	u32 tCH_min;
+	u32 tCHZ_max;
+	u32 tCLH_min;
+	u32 tCLR_min;
+	u32 tCLS_min;
+	u32 tCOH_min;
+	u32 tCS_min;
+	u32 tDH_min;
+	u32 tDS_min;
+	u32 tFEAT_max;
+	u32 tIR_min;
+	u32 tITC_max;
+	u32 tRC_min;
+	u32 tREA_max;
+	u32 tREH_min;
+	u32 tRHOH_min;
+	u32 tRHW_min;
+	u32 tRHZ_max;
+	u32 tRLOH_min;
+	u32 tRP_min;
+	u32 tRR_min;
+	u64 tRST_max;
+	u32 tWB_max;
+	u32 tWC_min;
+	u32 tWH_min;
+	u32 tWHR_min;
+	u32 tWP_min;
+	u32 tWW_min;
+};
+
+/**
+ * enum nand_data_interface_type - NAND interface timing type
+ * @NAND_SDR_IFACE:	Single Data Rate interface
+ */
+enum nand_data_interface_type {
+	NAND_SDR_IFACE,
+};
+
+/**
+ * struct nand_data_interface - NAND interface timing
+ * @type:	type of the timing
+ * @timings:	The timing, type according to @type
+ */
+struct nand_data_interface {
+	enum nand_data_interface_type type;
+	union {
+		struct nand_sdr_timings sdr;
+	} timings;
+};
+
+/**
+ * nand_get_sdr_timings - get SDR timing from data interface
+ * @conf:	The data interface
+ */
+static inline const struct nand_sdr_timings *
+nand_get_sdr_timings(const struct nand_data_interface *conf)
+{
+	if (conf->type != NAND_SDR_IFACE)
+		return ERR_PTR(-EINVAL);
+
+	return &conf->timings.sdr;
+}
+
+/**
  * struct nand_chip - NAND Private Flash Chip Data
  * @mtd:		MTD device registered to the MTD framework
  * @IO_ADDR_R:		[BOARDSPECIFIC] address to read the 8 I/O lines of the
@@ -1059,55 +1176,6 @@ void nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len);
 void nand_read_buf16(struct mtd_info *mtd, uint8_t *buf, int len);
 uint8_t nand_read_byte(struct mtd_info *mtd);
 
-/*
- * struct nand_sdr_timings - SDR NAND chip timings
- *
- * This struct defines the timing requirements of a SDR NAND chip.
- * These informations can be found in every NAND datasheets and the timings
- * meaning are described in the ONFI specifications:
- * www.onfi.org/~/media/ONFI/specs/onfi_3_1_spec.pdf (chapter 4.15 Timing
- * Parameters)
- *
- * All these timings are expressed in picoseconds.
- */
-
-struct nand_sdr_timings {
-	u32 tALH_min;
-	u32 tADL_min;
-	u32 tALS_min;
-	u32 tAR_min;
-	u32 tCEA_max;
-	u32 tCEH_min;
-	u32 tCH_min;
-	u32 tCHZ_max;
-	u32 tCLH_min;
-	u32 tCLR_min;
-	u32 tCLS_min;
-	u32 tCOH_min;
-	u32 tCS_min;
-	u32 tDH_min;
-	u32 tDS_min;
-	u32 tFEAT_max;
-	u32 tIR_min;
-	u32 tITC_max;
-	u32 tRC_min;
-	u32 tREA_max;
-	u32 tREH_min;
-	u32 tRHOH_min;
-	u32 tRHW_min;
-	u32 tRHZ_max;
-	u32 tRLOH_min;
-	u32 tRP_min;
-	u32 tRR_min;
-	u64 tRST_max;
-	u32 tWB_max;
-	u32 tWC_min;
-	u32 tWH_min;
-	u32 tWHR_min;
-	u32 tWP_min;
-	u32 tWW_min;
-};
-
 /* get timing characteristics from ONFI timing mode. */
 const struct nand_sdr_timings *onfi_async_timing_mode_to_sdr_timings(int mode);