Add support for the NAND flash controller found on NVIDIA
Tegra 2/3 SoCs.

Signed-off-by: Lucas Stach <d...@lynxeye.de>
Reviewed-by: Stefan Agner <ste...@agner.ch>
---
v2:
- remove Tegra 3 compatible
- remove useless part_probes
- don't store irq number
- use gpiod API instead of deprecated of_gpios
- don't store reset
- correct TIMING_TCS mask
- simplify irq handler
- correct timing calculations
- don't store buswidth
- drop compile test
- correct ECC handling

v3:
- remove superfluous NAND cap setting
- correct ECC layout
- don't flag ECC error for erased pages
- make MTD device name a bit human friendlier
- mark subpage writes as unsupported
- parse BBT on flash property

v4:
- report correct number of bitflips
- use DIV_ROUND_UP in timing calculation to avoid rounding errors
---
 MAINTAINERS                   |   6 +
 drivers/mtd/nand/Kconfig      |   6 +
 drivers/mtd/nand/Makefile     |   1 +
 drivers/mtd/nand/tegra_nand.c | 839 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 852 insertions(+)
 create mode 100644 drivers/mtd/nand/tegra_nand.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 747c653..fa813d1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10317,6 +10317,12 @@ M:     Laxman Dewangan <ldewan...@nvidia.com>
 S:     Supported
 F:     drivers/input/keyboard/tegra-kbc.c
 
+TEGRA NAND DRIVER
+M:     Lucas Stach <d...@lynxeye.de>
+S:     Maintained
+F:     Documentation/devicetree/bindings/mtd/nvidia,tegra20-nand.txt
+F:     drivers/mtd/nand/tegra_nand.c
+
 TEGRA PWM DRIVER
 M:     Thierry Reding <thierry.red...@gmail.com>
 S:     Supported
diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
index 3324281..a340338 100644
--- a/drivers/mtd/nand/Kconfig
+++ b/drivers/mtd/nand/Kconfig
@@ -535,4 +535,10 @@ config MTD_NAND_HISI504
        help
          Enables support for NAND controller on Hisilicon SoC Hip04.
 
+config MTD_NAND_TEGRA
+       tristate "Support for NAND on NVIDIA Tegra"
+       depends on ARCH_TEGRA
+       help
+         Enables support for NAND flash on NVIDIA Tegra SoC based boards.
+
 endif # MTD_NAND
diff --git a/drivers/mtd/nand/Makefile b/drivers/mtd/nand/Makefile
index 075a027..387a09b 100644
--- a/drivers/mtd/nand/Makefile
+++ b/drivers/mtd/nand/Makefile
@@ -54,5 +54,6 @@ obj-$(CONFIG_MTD_NAND_BCM47XXNFLASH)  += bcm47xxnflash/
 obj-$(CONFIG_MTD_NAND_SUNXI)           += sunxi_nand.o
 obj-$(CONFIG_MTD_NAND_HISI504)         += hisi504_nand.o
 obj-$(CONFIG_MTD_NAND_BRCMNAND)                += brcmnand/
+obj-$(CONFIG_MTD_NAND_TEGRA)           += tegra_nand.o
 
 nand-objs := nand_base.o nand_bbt.o nand_timings.o
diff --git a/drivers/mtd/nand/tegra_nand.c b/drivers/mtd/nand/tegra_nand.c
new file mode 100644
index 0000000..5ed8132
--- /dev/null
+++ b/drivers/mtd/nand/tegra_nand.c
@@ -0,0 +1,839 @@
+/*
+ * Copyright (C) 2014-2015 Lucas Stach <d...@lynxeye.de>
+ * Copyright (C) 2012 Avionic Design GmbH
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/mtd/nand.h>
+#include <linux/mtd/partitions.h>
+#include <linux/of_mtd.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+
+#define CMD                                    0x00
+#define   CMD_GO                               (1 << 31)
+#define   CMD_CLE                              (1 << 30)
+#define   CMD_ALE                              (1 << 29)
+#define   CMD_PIO                              (1 << 28)
+#define   CMD_TX                               (1 << 27)
+#define   CMD_RX                               (1 << 26)
+#define   CMD_SEC_CMD                          (1 << 25)
+#define   CMD_AFT_DAT                          (1 << 24)
+#define   CMD_TRANS_SIZE(x)                    (((x) & 0xf) << 20)
+#define   CMD_A_VALID                          (1 << 19)
+#define   CMD_B_VALID                          (1 << 18)
+#define   CMD_RD_STATUS_CHK                    (1 << 17)
+#define   CMD_RBSY_CHK                         (1 << 16)
+#define   CMD_CE(x)                            (1 << (8 + ((x) & 0x7)))
+#define   CMD_CLE_SIZE(x)                      (((x) & 0x3) << 4)
+#define   CMD_ALE_SIZE(x)                      (((x) & 0xf) << 0)
+
+#define STATUS                                 0x04
+
+#define ISR                                    0x08
+#define   ISR_CORRFAIL_ERR                     (1 << 24)
+#define   ISR_UND                              (1 << 7)
+#define   ISR_OVR                              (1 << 6)
+#define   ISR_CMD_DONE                         (1 << 5)
+#define   ISR_ECC_ERR                          (1 << 4)
+
+#define IER                                    0x0c
+#define   IER_ERR_TRIG_VAL(x)                  (((x) & 0xf) << 16)
+#define   IER_UND                              (1 << 7)
+#define   IER_OVR                              (1 << 6)
+#define   IER_CMD_DONE                         (1 << 5)
+#define   IER_ECC_ERR                          (1 << 4)
+#define   IER_GIE                              (1 << 0)
+
+#define CFG                                    0x10
+#define   CFG_HW_ECC                           (1 << 31)
+#define   CFG_ECC_SEL                          (1 << 30)
+#define   CFG_ERR_COR                          (1 << 29)
+#define   CFG_PIPE_EN                          (1 << 28)
+#define   CFG_TVAL_4                           (0 << 24)
+#define   CFG_TVAL_6                           (1 << 24)
+#define   CFG_TVAL_8                           (2 << 24)
+#define   CFG_SKIP_SPARE                       (1 << 23)
+#define   CFG_BUS_WIDTH_8                      (0 << 21)
+#define   CFG_BUS_WIDTH_16                     (1 << 21)
+#define   CFG_COM_BSY                          (1 << 20)
+#define   CFG_PS_256                           (0 << 16)
+#define   CFG_PS_512                           (1 << 16)
+#define   CFG_PS_1024                          (2 << 16)
+#define   CFG_PS_2048                          (3 << 16)
+#define   CFG_PS_4096                          (4 << 16)
+#define   CFG_SKIP_SPARE_SIZE_4                        (0 << 14)
+#define   CFG_SKIP_SPARE_SIZE_8                        (1 << 14)
+#define   CFG_SKIP_SPARE_SIZE_12               (2 << 14)
+#define   CFG_SKIP_SPARE_SIZE_16               (3 << 14)
+#define   CFG_TAG_BYTE_SIZE(x)                 ((x) & 0xff)
+
+#define TIMING_1                               0x14
+#define   TIMING_TRP_RESP(x)                   (((x) & 0xf) << 28)
+#define   TIMING_TWB(x)                                (((x) & 0xf) << 24)
+#define   TIMING_TCR_TAR_TRR(x)                        (((x) & 0xf) << 20)
+#define   TIMING_TWHR(x)                       (((x) & 0xf) << 16)
+#define   TIMING_TCS(x)                                (((x) & 0x3) << 14)
+#define   TIMING_TWH(x)                                (((x) & 0x3) << 12)
+#define   TIMING_TWP(x)                                (((x) & 0xf) <<  8)
+#define   TIMING_TRH(x)                                (((x) & 0xf) <<  4)
+#define   TIMING_TRP(x)                                (((x) & 0xf) <<  0)
+
+#define RESP                                   0x18
+
+#define TIMING_2                               0x1c
+#define   TIMING_TADL(x)                       ((x) & 0xf)
+
+#define CMD_1                                  0x20
+#define CMD_2                                  0x24
+#define ADDR_1                                 0x28
+#define ADDR_2                                 0x2c
+
+#define DMA_CTRL                               0x30
+#define   DMA_CTRL_GO                          (1 << 31)
+#define   DMA_CTRL_IN                          (0 << 30)
+#define   DMA_CTRL_OUT                         (1 << 30)
+#define   DMA_CTRL_PERF_EN                     (1 << 29)
+#define   DMA_CTRL_IE_DONE                     (1 << 28)
+#define   DMA_CTRL_REUSE                       (1 << 27)
+#define   DMA_CTRL_BURST_1                     (2 << 24)
+#define   DMA_CTRL_BURST_4                     (3 << 24)
+#define   DMA_CTRL_BURST_8                     (4 << 24)
+#define   DMA_CTRL_BURST_16                    (5 << 24)
+#define   DMA_CTRL_IS_DONE                     (1 << 20)
+#define   DMA_CTRL_EN_A                                (1 <<  2)
+#define   DMA_CTRL_EN_B                                (1 <<  1)
+
+#define DMA_CFG_A                              0x34
+#define DMA_CFG_B                              0x38
+
+#define FIFO_CTRL                              0x3c
+#define   FIFO_CTRL_CLR_ALL                    (1 << 3)
+
+#define DATA_PTR                               0x40
+#define TAG_PTR                                        0x44
+#define ECC_PTR                                        0x48
+
+#define DEC_STATUS                             0x4c
+#define   DEC_STATUS_A_ECC_FAIL                        (1 << 1)
+#define   DEC_STATUS_ERR_COUNT_MASK            0x00ff0000
+#define   DEC_STATUS_ERR_COUNT_SHIFT           16
+
+#define HWSTATUS_CMD                           0x50
+#define HWSTATUS_MASK                          0x54
+#define   HWSTATUS_RDSTATUS_MASK(x)            (((x) & 0xff) << 24)
+#define   HWSTATUS_RDSTATUS_VALUE(x)           (((x) & 0xff) << 16)
+#define   HWSTATUS_RBSY_MASK(x)                        (((x) & 0xff) << 8)
+#define   HWSTATUS_RBSY_VALUE(x)               (((x) & 0xff) << 0)
+
+#define DEC_STAT_BUF                           0xd4
+#define   DEC_STAT_BUF_MAX_CORR_CNT_MASK       0x00001f00
+#define   DEC_STAT_BUF_MAX_CORR_CNT_SHIFT      8
+
+struct tegra_nand {
+       void __iomem *regs;
+       struct clk *clk;
+       struct gpio_desc *wp_gpio;
+
+       struct nand_chip chip;
+       struct mtd_info mtd;
+       struct device *dev;
+
+       struct completion command_complete;
+       struct completion dma_complete;
+       bool last_read_error;
+
+       dma_addr_t data_dma;
+       void *data_buf;
+       dma_addr_t oob_dma;
+       void *oob_buf;
+
+       int cur_chip;
+};
+
+static inline struct tegra_nand *to_tegra_nand(struct mtd_info *mtd)
+{
+       return container_of(mtd, struct tegra_nand, mtd);
+}
+
+static struct nand_ecclayout tegra_nand_oob_16 = {
+       .eccbytes = 4,
+       .eccpos = { 4, 5, 6, 7 },
+       .oobfree = {
+               { .offset = 8, . length = 8 }
+       }
+};
+
+static struct nand_ecclayout tegra_nand_oob_64 = {
+       .eccbytes = 36,
+       .eccpos = {
+                4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
+               20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
+               36, 37, 38, 39
+       },
+       .oobfree = {
+               { .offset = 40, .length = 24 }
+       }
+};
+
+static struct nand_ecclayout tegra_nand_oob_128 = {
+       .eccbytes = 72,
+       .eccpos = {
+                4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
+               20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
+               36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,
+               52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67,
+               68, 69, 70, 71, 72, 73, 74, 75
+       },
+       .oobfree = {
+               { .offset = 76, .length = 52 }
+       }
+};
+
+static struct nand_ecclayout tegra_nand_oob_224 = {
+       .eccbytes = 144,
+       .eccpos = {
+                 4,   5,   6,   7,   8,   9,  10,  11,  12,  13,  14,  15,  16,
+                17,  18,  19,  20,  21,  22,  23,  24,  25,  26,  27,  28,  29,
+                30,  31,  32,  33,  34,  35,  36,  37,  38,  39,  40,  41,  42,
+                43,  44,  45,  46,  47,  48,  49,  50,  51,  52,  53,  54,  55,
+                56,  57,  58,  59,  60,  61,  62,  63,  64,  65,  66,  67,  68,
+                69,  70,  71,  72,  73,  74,  75,  76,  77,  78,  79,  80,  81,
+                82,  83,  84,  85,  86,  87,  88,  89,  90,  91,  92,  93,  94,
+                95,  96,  97,  98,  99, 100, 101, 102, 103, 104, 105, 106, 107,
+               108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120,
+               121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133,
+               134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146,
+               147
+       },
+       .oobfree = {
+               { .offset = 148, .length = 76 }
+       }
+};
+
+static irqreturn_t tegra_nand_irq(int irq, void *data)
+{
+       struct tegra_nand *nand = data;
+       u32 isr, dma;
+
+       isr = readl(nand->regs + ISR);
+       dma = readl(nand->regs + DMA_CTRL);
+
+       if (!isr && !(dma & DMA_CTRL_IS_DONE))
+               return IRQ_NONE;
+
+       if (isr & ISR_CORRFAIL_ERR)
+               nand->last_read_error = true;
+
+       if (isr & ISR_CMD_DONE)
+               complete(&nand->command_complete);
+
+       if (isr & ISR_UND)
+               dev_dbg(nand->dev, "FIFO underrun\n");
+
+       if (isr & ISR_OVR)
+               dev_dbg(nand->dev, "FIFO overrun\n");
+
+       /* handle DMA interrupts */
+       if (dma & DMA_CTRL_IS_DONE) {
+               writel(dma, nand->regs + DMA_CTRL);
+               complete(&nand->dma_complete);
+       }
+
+       /* clear interrupts */
+       writel(isr, nand->regs + ISR);
+
+       return IRQ_HANDLED;
+}
+
+static void tegra_nand_command(struct mtd_info *mtd, unsigned int command,
+                              int column, int page_addr)
+{
+       struct tegra_nand *nand = to_tegra_nand(mtd);
+       u32 value;
+
+       switch (command) {
+       case NAND_CMD_READOOB:
+               column += mtd->writesize;
+               /* fall-through */
+
+       case NAND_CMD_READ0:
+               writel(NAND_CMD_READ0, nand->regs + CMD_1);
+               writel(NAND_CMD_READSTART, nand->regs + CMD_2);
+
+               value = (page_addr << 16) | (column & 0xffff);
+               writel(value, nand->regs + ADDR_1);
+
+               value = page_addr >> 16;
+               writel(value, nand->regs + ADDR_2);
+
+               value = CMD_CLE | CMD_ALE | CMD_ALE_SIZE(4) | CMD_SEC_CMD |
+                       CMD_RBSY_CHK | CMD_CE(nand->cur_chip) | CMD_GO;
+               writel(value, nand->regs + CMD);
+               break;
+
+       case NAND_CMD_SEQIN:
+               writel(NAND_CMD_SEQIN, nand->regs + CMD_1);
+
+               value = (page_addr << 16) | (column & 0xffff);
+               writel(value, nand->regs + ADDR_1);
+
+               value = page_addr >> 16;
+               writel(value, nand->regs + ADDR_2);
+
+               value = CMD_CLE | CMD_ALE | CMD_ALE_SIZE(4) |
+                       CMD_CE(nand->cur_chip) | CMD_GO;
+               writel(value, nand->regs + CMD);
+               break;
+
+       case NAND_CMD_PAGEPROG:
+               writel(NAND_CMD_PAGEPROG, nand->regs + CMD_1);
+
+               value = CMD_CLE | CMD_CE(nand->cur_chip) | CMD_GO;
+               writel(value, nand->regs + CMD);
+               break;
+
+       case NAND_CMD_READID:
+               writel(NAND_CMD_READID, nand->regs + CMD_1);
+               writel(column & 0xff, nand->regs + ADDR_1);
+
+               value = CMD_GO | CMD_CLE | CMD_ALE | CMD_CE(nand->cur_chip);
+               writel(value, nand->regs + CMD);
+               break;
+
+       case NAND_CMD_ERASE1:
+               writel(NAND_CMD_ERASE1, nand->regs + CMD_1);
+               writel(NAND_CMD_ERASE2, nand->regs + CMD_2);
+               writel(page_addr, nand->regs + ADDR_1);
+
+               value = CMD_GO | CMD_CLE | CMD_ALE | CMD_ALE_SIZE(2) |
+                       CMD_SEC_CMD | CMD_RBSY_CHK | CMD_CE(nand->cur_chip);
+               writel(value, nand->regs + CMD);
+               break;
+
+       case NAND_CMD_ERASE2:
+               return;
+
+       case NAND_CMD_STATUS:
+               writel(NAND_CMD_STATUS, nand->regs + CMD_1);
+
+               value = CMD_GO | CMD_CLE | CMD_CE(nand->cur_chip);
+               writel(value, nand->regs + CMD);
+               break;
+
+       case NAND_CMD_PARAM:
+               writel(NAND_CMD_PARAM, nand->regs + CMD_1);
+               writel(column & 0xff, nand->regs + ADDR_1);
+               value = CMD_GO | CMD_CLE | CMD_ALE | CMD_CE(nand->cur_chip);
+               writel(value, nand->regs + CMD);
+               break;
+
+       case NAND_CMD_RESET:
+               writel(NAND_CMD_RESET, nand->regs + CMD_1);
+
+               value = CMD_GO | CMD_CLE | CMD_CE(nand->cur_chip);
+               writel(value, nand->regs + CMD);
+               break;
+
+       default:
+               dev_warn(nand->dev, "unsupported command: %x\n", command);
+               return;
+       }
+
+       wait_for_completion(&nand->command_complete);
+}
+
+static void tegra_nand_select_chip(struct mtd_info *mtd, int chip)
+{
+       struct tegra_nand *nand = to_tegra_nand(mtd);
+
+       nand->cur_chip = chip;
+}
+
+static uint8_t tegra_nand_read_byte(struct mtd_info *mtd)
+{
+       struct tegra_nand *nand = to_tegra_nand(mtd);
+       u32 value;
+
+       value = CMD_TRANS_SIZE(0) | CMD_CE(nand->cur_chip) |
+               CMD_PIO | CMD_RX | CMD_A_VALID | CMD_GO;
+
+       writel(value, nand->regs + CMD);
+       wait_for_completion(&nand->command_complete);
+
+       return readl(nand->regs + RESP) & 0xff;
+}
+
+static void tegra_nand_read_buf(struct mtd_info *mtd, uint8_t *buffer,
+                               int length)
+{
+       struct tegra_nand *nand = to_tegra_nand(mtd);
+       size_t i;
+
+       for (i = 0; i < length; i += 4) {
+               u32 value;
+               size_t n = min_t(size_t, length - i, 4);
+
+               value = CMD_GO | CMD_PIO | CMD_RX | CMD_A_VALID |
+                       CMD_CE(nand->cur_chip) | CMD_TRANS_SIZE(n - 1);
+
+               writel(value, nand->regs + CMD);
+               wait_for_completion(&nand->command_complete);
+
+               value = readl(nand->regs + RESP);
+               memcpy(buffer + i, &value, n);
+       }
+}
+
+static void tegra_nand_write_buf(struct mtd_info *mtd, const uint8_t *buffer,
+                                int length)
+{
+       struct tegra_nand *nand = to_tegra_nand(mtd);
+       size_t i;
+
+       for (i = 0; i < length; i += 4) {
+               u32 value;
+               size_t n = min_t(size_t, length - i, 4);
+
+               memcpy(&value, buffer + i, n);
+               writel(value, nand->regs + RESP);
+
+               value = CMD_GO | CMD_PIO | CMD_TX | CMD_A_VALID |
+                       CMD_CE(nand->cur_chip) | CMD_TRANS_SIZE(n - 1);
+
+               writel(value, nand->regs + CMD);
+               wait_for_completion(&nand->command_complete);
+       }
+}
+
+static int tegra_nand_read_page(struct mtd_info *mtd, struct nand_chip *chip,
+                               uint8_t *buf, int oob_required, int page)
+{
+       struct tegra_nand *nand = to_tegra_nand(mtd);
+       u32 value;
+
+       value = readl(nand->regs + CFG);
+       value |= CFG_HW_ECC | CFG_ERR_COR;
+       writel(value, nand->regs + CFG);
+
+       writel(mtd->writesize - 1, nand->regs + DMA_CFG_A);
+       writel(nand->data_dma, nand->regs + DATA_PTR);
+
+       if (oob_required) {
+               writel(chip->ecc.layout->oobfree[0].length - 1,
+                      nand->regs + DMA_CFG_B);
+               writel(nand->oob_dma, nand->regs + TAG_PTR);
+       } else {
+               writel(0, nand->regs + DMA_CFG_B);
+               writel(0, nand->regs + TAG_PTR);
+       }
+
+       value = DMA_CTRL_GO | DMA_CTRL_IN | DMA_CTRL_PERF_EN |
+               DMA_CTRL_REUSE | DMA_CTRL_IE_DONE | DMA_CTRL_IS_DONE |
+               DMA_CTRL_BURST_8 | DMA_CTRL_EN_A;
+       if (oob_required)
+               value |= DMA_CTRL_EN_B;
+       writel(value, nand->regs + DMA_CTRL);
+
+       value = CMD_GO | CMD_RX | CMD_TRANS_SIZE(8) |
+               CMD_A_VALID | CMD_CE(nand->cur_chip);
+       if (oob_required)
+               value |= CMD_B_VALID;
+       writel(value, nand->regs + CMD);
+
+       wait_for_completion(&nand->command_complete);
+       wait_for_completion(&nand->dma_complete);
+
+       if (oob_required)
+               memcpy(chip->oob_poi,
+                      nand->oob_buf + chip->ecc.layout->oobfree[0].offset,
+                      chip->ecc.layout->oobfree[0].length);
+       memcpy(buf, nand->data_buf, mtd->writesize);
+
+       value = readl(nand->regs + CFG);
+       value &= ~(CFG_HW_ECC | CFG_ERR_COR);
+       writel(value, nand->regs + CFG);
+
+       value = readl(nand->regs + DEC_STATUS);
+       if (value & DEC_STATUS_A_ECC_FAIL) {
+               /*
+                * The ECC isn't smart enough to figure out if a page is
+                * completely erased and flags an error in this case. So we
+                * check the read data here to figure out if it's a legitimate
+                * error or a false positive.
+                */
+               int i;
+               u32 *data = (u32 *)buf;
+               for (i = 0; i < mtd->writesize / 4; i++) {
+                       if (data[i] != 0xffffffff) {
+                               mtd->ecc_stats.failed++;
+                               return -EBADMSG;
+                       }
+               }
+               return 0;
+       }
+
+       if (nand->last_read_error) {
+               value = readl(nand->regs + DEC_STAT_BUF);
+               value = (value & DEC_STAT_BUF_MAX_CORR_CNT_MASK) >>
+                       DEC_STAT_BUF_MAX_CORR_CNT_SHIFT;
+               /*
+                * The value returned in the register is the maximum of
+                * bitflips encountered in any of the ECC regions. As there is
+                * no way to get the number of bitflips in a specific regions
+                * we are not able to deliver correct stats but instead
+                * overestimate the number of corrected bitflips by assuming
+                * that all regions encountered the maximum number of bitflips.
+                */
+               mtd->ecc_stats.corrected += value * chip->ecc.steps;
+               nand->last_read_error = false;
+               return value;
+       }
+
+       return 0;
+}
+
+static int tegra_nand_write_page(struct mtd_info *mtd, struct nand_chip *chip,
+                                const uint8_t *buf, int oob_required)
+{
+       struct tegra_nand *nand = to_tegra_nand(mtd);
+       unsigned long value;
+
+       value = readl(nand->regs + CFG);
+       value |= CFG_HW_ECC | CFG_ERR_COR;
+       writel(value, nand->regs + CFG);
+
+       memcpy(nand->data_buf, buf, mtd->writesize);
+
+       writel(mtd->writesize - 1, nand->regs + DMA_CFG_A);
+       writel(nand->data_dma, nand->regs + DATA_PTR);
+
+       if (oob_required) {
+               memcpy(nand->oob_buf,
+                      chip->oob_poi + chip->ecc.layout->oobfree[0].offset,
+                      chip->ecc.layout->oobfree[0].length);
+               writel(chip->ecc.layout->oobfree[0].length - 1,
+                      nand->regs + DMA_CFG_B);
+               writel(nand->oob_dma, nand->regs + TAG_PTR);
+       } else {
+               writel(0, nand->regs + DMA_CFG_B);
+               writel(0, nand->regs + TAG_PTR);
+       }
+
+       value = DMA_CTRL_GO | DMA_CTRL_OUT | DMA_CTRL_PERF_EN |
+               DMA_CTRL_IE_DONE | DMA_CTRL_IS_DONE |
+               DMA_CTRL_BURST_8 | DMA_CTRL_EN_A;
+       if (oob_required)
+               value |= DMA_CTRL_EN_B;
+       writel(value, nand->regs + DMA_CTRL);
+
+       value = CMD_GO | CMD_TX | CMD_A_VALID | CMD_TRANS_SIZE(8) |
+               CMD_CE(nand->cur_chip);
+       if (oob_required)
+               value |= CMD_B_VALID;
+       writel(value, nand->regs + CMD);
+
+       wait_for_completion(&nand->command_complete);
+       wait_for_completion(&nand->dma_complete);
+
+       value = readl(nand->regs + CFG);
+       value &= ~(CFG_HW_ECC | CFG_ERR_COR);
+       writel(value, nand->regs + CFG);
+
+       return 0;
+}
+
+static void tegra_nand_setup_timing(struct tegra_nand *nand, int mode)
+{
+       /*
+        * The period (and all other timings in this function) is in ps,
+        * so need to take care here to avoid integer overflows.
+        */
+       unsigned int rate = clk_get_rate(nand->clk) / 1000000;
+       unsigned int period = DIV_ROUND_UP(1000000, rate);
+       const struct nand_sdr_timings *timings;
+       u32 val, reg = 0;
+
+       timings = onfi_async_timing_mode_to_sdr_timings(mode);
+
+       val = DIV_ROUND_UP(max3(timings->tAR_min, timings->tRR_min,
+                               timings->tRC_min), period);
+       if (val > 2)
+               val -= 3;
+       reg |= TIMING_TCR_TAR_TRR(val);
+
+       val = DIV_ROUND_UP(max(max(timings->tCS_min, timings->tCH_min),
+                                  max(timings->tALS_min, timings->tALH_min)),
+                          period);
+       if (val > 1)
+               val -= 2;
+       reg |= TIMING_TCS(val);
+
+       val = DIV_ROUND_UP(max(timings->tRP_min, timings->tREA_max) + 6000,
+                          period);
+       reg |= TIMING_TRP(val) | TIMING_TRP_RESP(val);
+
+       reg |= TIMING_TWB(DIV_ROUND_UP(timings->tWB_max, period));
+       reg |= TIMING_TWHR(DIV_ROUND_UP(timings->tWHR_min, period));
+       reg |= TIMING_TWH(DIV_ROUND_UP(timings->tWH_min, period));
+       reg |= TIMING_TWP(DIV_ROUND_UP(timings->tWP_min, period));
+       reg |= TIMING_TRH(DIV_ROUND_UP(timings->tRHW_min, period));
+
+       writel(reg, nand->regs + TIMING_1);
+
+       val = DIV_ROUND_UP(timings->tADL_min, period);
+       if (val > 2)
+               val -= 3;
+       reg = TIMING_TADL(val);
+
+       writel(reg, nand->regs + TIMING_2);
+}
+
+static void tegra_nand_setup_chiptiming(struct tegra_nand *nand)
+{
+       struct nand_chip *chip = &nand->chip;
+       int mode;
+
+       mode = onfi_get_async_timing_mode(chip);
+       if (mode == ONFI_TIMING_MODE_UNKNOWN)
+               mode = chip->onfi_timing_mode_default;
+       else
+               mode = fls(mode);
+
+       tegra_nand_setup_timing(nand, mode);
+}
+
+static int tegra_nand_probe(struct platform_device *pdev)
+{
+       struct reset_control *rst;
+       struct tegra_nand *nand;
+       struct nand_chip *chip;
+       struct mtd_info *mtd;
+       struct resource *res;
+       unsigned long value;
+       int irq, err = 0;
+
+       nand = devm_kzalloc(&pdev->dev, sizeof(*nand), GFP_KERNEL);
+       if (!nand)
+               return -ENOMEM;
+
+       nand->dev = &pdev->dev;
+
+       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+       nand->regs = devm_ioremap_resource(&pdev->dev, res);
+       if (IS_ERR(nand->regs))
+               return PTR_ERR(nand->regs);
+
+       irq = platform_get_irq(pdev, 0);
+       err = devm_request_irq(&pdev->dev, irq, tegra_nand_irq, 0,
+                              dev_name(&pdev->dev), nand);
+       if (err)
+               return err;
+
+       rst = devm_reset_control_get(&pdev->dev, "nand");
+       if (IS_ERR(rst))
+               return PTR_ERR(rst);
+
+       nand->clk = devm_clk_get(&pdev->dev, "nand");
+       if (IS_ERR(nand->clk))
+               return PTR_ERR(nand->clk);
+
+       nand->wp_gpio = gpiod_get_optional(&pdev->dev, "wp-gpios",
+                                          GPIOD_OUT_HIGH);
+       if (IS_ERR(nand->wp_gpio))
+               return PTR_ERR(nand->wp_gpio);
+
+       err = clk_prepare_enable(nand->clk);
+       if (err)
+               return err;
+
+       reset_control_assert(rst);
+       udelay(2);
+       reset_control_deassert(rst);
+
+       value = HWSTATUS_RDSTATUS_MASK(1) | HWSTATUS_RDSTATUS_VALUE(0) |
+               HWSTATUS_RBSY_MASK(NAND_STATUS_READY) |
+               HWSTATUS_RBSY_VALUE(NAND_STATUS_READY);
+       writel(NAND_CMD_STATUS, nand->regs + HWSTATUS_CMD);
+       writel(value, nand->regs + HWSTATUS_MASK);
+
+       init_completion(&nand->command_complete);
+       init_completion(&nand->dma_complete);
+
+       mtd = &nand->mtd;
+       mtd->name = "tegra_nand";
+       mtd->owner = THIS_MODULE;
+       mtd->priv = &nand->chip;
+
+       /* clear interrupts */
+       value = readl(nand->regs + ISR);
+       writel(value, nand->regs + ISR);
+
+       writel(DMA_CTRL_IS_DONE, nand->regs + DMA_CTRL);
+
+       /* enable interrupts */
+       value = IER_UND | IER_OVR | IER_CMD_DONE | IER_ECC_ERR | IER_GIE;
+       writel(value, nand->regs + IER);
+
+       /* reset config */
+       writel(0, nand->regs + CFG);
+
+       chip = &nand->chip;
+       chip->dn = pdev->dev.of_node;
+       chip->options = NAND_NO_SUBPAGE_WRITE;
+       chip->cmdfunc = tegra_nand_command;
+       chip->select_chip = tegra_nand_select_chip;
+       chip->read_byte = tegra_nand_read_byte;
+       chip->read_buf = tegra_nand_read_buf;
+       chip->write_buf = tegra_nand_write_buf;
+
+       tegra_nand_setup_timing(nand, 0);
+
+       err = nand_scan_ident(mtd, 1, NULL);
+       if (err)
+               return err;
+
+       if (chip->bbt_options & NAND_BBT_USE_FLASH)
+               chip->bbt_options |= NAND_BBT_NO_OOB;
+
+       nand->data_buf = dmam_alloc_coherent(&pdev->dev, mtd->writesize,
+                                           &nand->data_dma, GFP_KERNEL);
+       if (!nand->data_buf)
+               return -ENOMEM;
+
+       nand->oob_buf = dmam_alloc_coherent(&pdev->dev, mtd->oobsize,
+                                           &nand->oob_dma, GFP_KERNEL);
+       if (!nand->oob_buf)
+               return -ENOMEM;
+
+       chip->ecc.mode = NAND_ECC_HW;
+       chip->ecc.size = 512;
+       chip->ecc.bytes = mtd->oobsize;
+       chip->ecc.read_page = tegra_nand_read_page;
+       chip->ecc.write_page = tegra_nand_write_page;
+
+       value = readl(nand->regs + CFG);
+       value |=  CFG_PIPE_EN | CFG_SKIP_SPARE | CFG_SKIP_SPARE_SIZE_4;
+
+       if (chip->options & NAND_BUSWIDTH_16)
+               value |= CFG_BUS_WIDTH_16;
+
+       switch (mtd->oobsize) {
+       case 16:
+               chip->ecc.layout = &tegra_nand_oob_16;
+               chip->ecc.strength = 1;
+               value |= CFG_TAG_BYTE_SIZE(tegra_nand_oob_16.oobfree[0].length
+                        - 1);
+               break;
+       case 64:
+               chip->ecc.layout = &tegra_nand_oob_64;
+               chip->ecc.strength = 8;
+               value |= CFG_ECC_SEL | CFG_TVAL_8 |
+                        CFG_TAG_BYTE_SIZE(tegra_nand_oob_64.oobfree[0].length
+                        - 1);
+               break;
+       case 128:
+               chip->ecc.layout = &tegra_nand_oob_128;
+               chip->ecc.strength = 8;
+               value |= CFG_ECC_SEL | CFG_TVAL_8 |
+                        CFG_TAG_BYTE_SIZE(tegra_nand_oob_128.oobfree[0].length
+                        - 1);
+               break;
+       case 224:
+               chip->ecc.layout = &tegra_nand_oob_224;
+               chip->ecc.strength = 8;
+               value |= CFG_ECC_SEL | CFG_TVAL_8 |
+                        CFG_TAG_BYTE_SIZE(tegra_nand_oob_224.oobfree[0].length
+                        - 1);
+               break;
+       default:
+               dev_err(&pdev->dev, "unhandled OOB size %d\n", mtd->oobsize);
+               return -ENODEV;
+       }
+
+       switch (mtd->writesize) {
+       case 256:
+               value |= CFG_PS_256;
+               break;
+       case 512:
+               value |= CFG_PS_512;
+               break;
+       case 1024:
+               value |= CFG_PS_1024;
+               break;
+       case 2048:
+               value |= CFG_PS_2048;
+               break;
+       case 4096:
+               value |= CFG_PS_4096;
+               break;
+       default:
+               dev_err(&pdev->dev, "unhandled writesize %d\n", mtd->writesize);
+               return -ENODEV;
+       }
+
+       writel(value, nand->regs + CFG);
+
+       tegra_nand_setup_chiptiming(nand);
+
+       err = nand_scan_tail(mtd);
+       if (err)
+               return err;
+
+       err = mtd_device_parse_register(mtd, NULL,
+                                       &(struct mtd_part_parser_data) {
+                                               .of_node = pdev->dev.of_node,
+                                       },
+                                       NULL, 0);
+       if (err)
+               return err;
+
+       platform_set_drvdata(pdev, nand);
+
+       return 0;
+}
+
+static int tegra_nand_remove(struct platform_device *pdev)
+{
+       struct tegra_nand *nand = platform_get_drvdata(pdev);
+
+       nand_release(&nand->mtd);
+
+       clk_disable_unprepare(nand->clk);
+
+       return 0;
+}
+
+static const struct of_device_id tegra_nand_of_match[] = {
+       { .compatible = "nvidia,tegra20-nand" },
+       { /* sentinel */ }
+};
+
+static struct platform_driver tegra_nand_driver = {
+       .driver = {
+               .name = "tegra-nand",
+               .of_match_table = tegra_nand_of_match,
+       },
+       .probe = tegra_nand_probe,
+       .remove = tegra_nand_remove,
+};
+module_platform_driver(tegra_nand_driver);
+
+MODULE_DESCRIPTION("NVIDIA Tegra NAND driver");
+MODULE_AUTHOR("Thierry Reding <thierry.red...@avionic-design.de");
+MODULE_AUTHOR("Lucas Stach <d...@lynxeye.de");
+MODULE_LICENSE("GPL v2");
+MODULE_DEVICE_TABLE(of, tegra_nand_of_match);
-- 
2.4.3

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