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mtd: nand: sunxi: Replace failsafe timing cfg with calculated value

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The TIMING_CFG register was previously statically set to a magic value
(extracted from Allwinner's BSP) when initializing the NAND controller.
Now that we have more details about the TIMING_CFG register layout
(extracted from the A83 user manual) we can dynamically calculate the
appropriate value for each NAND chip and set it when selecting the
chip.

Signed-off-by: Roy Spliet <r.spliet@ultimaker.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
This commit is contained in:
Roy Spliet 2015-06-26 11:00:10 +02:00 committed by Brian Norris
parent 0db7fae273
commit 9c618292db
1 changed files with 68 additions and 5 deletions
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73
drivers/mtd/nand/sunxi_nand.c
View file

@ -99,6 +99,12 @@
NFC_CMD_INT_ENABLE | \
NFC_DMA_INT_ENABLE)
/* define NFC_TIMING_CFG register layout */
#define NFC_TIMING_CFG(tWB, tADL, tWHR, tRHW, tCAD) \
(((tWB) & 0x3) | (((tADL) & 0x3) << 2) | \
(((tWHR) & 0x3) << 4) | (((tRHW) & 0x3) << 6) | \
(((tCAD) & 0x7) << 8))
/* define bit use in NFC_CMD */
#define NFC_CMD_LOW_BYTE GENMASK(7, 0)
#define NFC_CMD_HIGH_BYTE GENMASK(15, 8)
@ -208,6 +214,7 @@ struct sunxi_nand_hw_ecc {
* @nand: base NAND chip structure
* @mtd: base MTD structure
* @clk_rate: clk_rate required for this NAND chip
* @timing_cfg TIMING_CFG register value for this NAND chip
* @selected: current active CS
* @nsels: number of CS lines required by the NAND chip
* @sels: array of CS lines descriptions
@ -217,6 +224,7 @@ struct sunxi_nand_chip {
struct nand_chip nand;
struct mtd_info mtd;
unsigned long clk_rate;
u32 timing_cfg;
int selected;
int nsels;
struct sunxi_nand_chip_sel sels[0];
@ -403,6 +411,7 @@ static void sunxi_nfc_select_chip(struct mtd_info *mtd, int chip)
}
}
writel(sunxi_nand->timing_cfg, nfc->regs + NFC_REG_TIMING_CFG);
writel(ctl, nfc->regs + NFC_REG_CTL);
sunxi_nand->selected = chip;
@ -807,10 +816,33 @@ static int sunxi_nfc_hw_syndrome_ecc_write_page(struct mtd_info *mtd,
return 0;
}
static const s32 tWB_lut[] = {6, 12, 16, 20};
static const s32 tRHW_lut[] = {4, 8, 12, 20};
static int _sunxi_nand_lookup_timing(const s32 *lut, int lut_size, u32 duration,
u32 clk_period)
{
u32 clk_cycles = DIV_ROUND_UP(duration, clk_period);
int i;
for (i = 0; i < lut_size; i++) {
if (clk_cycles <= lut[i])
return i;
}
/* Doesn't fit */
return -EINVAL;
}
#define sunxi_nand_lookup_timing(l, p, c) \
_sunxi_nand_lookup_timing(l, ARRAY_SIZE(l), p, c)
static int sunxi_nand_chip_set_timings(struct sunxi_nand_chip *chip,
const struct nand_sdr_timings *timings)
{
struct sunxi_nfc *nfc = to_sunxi_nfc(chip->nand.controller);
u32 min_clk_period = 0;
s32 tWB, tADL, tWHR, tRHW, tCAD;
/* T1 <=> tCLS */
if (timings->tCLS_min > min_clk_period)
@ -872,6 +904,41 @@ static int sunxi_nand_chip_set_timings(struct sunxi_nand_chip *chip,
if (timings->tWC_min > (min_clk_period * 2))
min_clk_period = DIV_ROUND_UP(timings->tWC_min, 2);
/* T16 - T19 + tCAD */
tWB = sunxi_nand_lookup_timing(tWB_lut, timings->tWB_max,
min_clk_period);
if (tWB < 0) {
dev_err(nfc->dev, "unsupported tWB\n");
return tWB;
}
tADL = DIV_ROUND_UP(timings->tADL_min, min_clk_period) >> 3;
if (tADL > 3) {
dev_err(nfc->dev, "unsupported tADL\n");
return -EINVAL;
}
tWHR = DIV_ROUND_UP(timings->tWHR_min, min_clk_period) >> 3;
if (tWHR > 3) {
dev_err(nfc->dev, "unsupported tWHR\n");
return -EINVAL;
}
tRHW = sunxi_nand_lookup_timing(tRHW_lut, timings->tRHW_min,
min_clk_period);
if (tRHW < 0) {
dev_err(nfc->dev, "unsupported tRHW\n");
return tRHW;
}
/*
* TODO: according to ONFI specs this value only applies for DDR NAND,
* but Allwinner seems to set this to 0x7. Mimic them for now.
*/
tCAD = 0x7;
/* TODO: A83 has some more bits for CDQSS, CS, CLHZ, CCS, WC */
chip->timing_cfg = NFC_TIMING_CFG(tWB, tADL, tWHR, tRHW, tCAD);
/* Convert min_clk_period from picoseconds to nanoseconds */
min_clk_period = DIV_ROUND_UP(min_clk_period, 1000);
@ -884,8 +951,6 @@ static int sunxi_nand_chip_set_timings(struct sunxi_nand_chip *chip,
*/
chip->clk_rate = (2 * NSEC_PER_SEC) / min_clk_period;
/* TODO: configure T16-T19 */
return 0;
}
@ -1377,11 +1442,9 @@ static int sunxi_nfc_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, nfc);
/*
* TODO: replace these magic values with proper flags as soon as we
* know what they are encoding.
* TODO: replace this magic value with EDO flag
*/
writel(0x100, nfc->regs + NFC_REG_TIMING_CTL);
writel(0x7ff, nfc->regs + NFC_REG_TIMING_CFG);
ret = sunxi_nand_chips_init(dev, nfc);
if (ret) {