[PATCH v1 2/2] mtd: rawnand: meson: support R/W mode for boot ROM

[Arseniy Krasnov <avkrasnov@salutedevices.com>]

Boot ROM code on Meson requires that some pages on NAND must be written
in special mode: "short" ECC mode where each block is 384 bytes and
scrambling mode is on. Such pages located with the specified interval
within specified offset. Both interval and offset are located in the
device tree and used by driver if 'nand-is-boot-medium' is set for
NAND chip.

Signed-off-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
---
 drivers/mtd/nand/raw/meson_nand.c | 88 +++++++++++++++++++++----------
 1 file changed, 59 insertions(+), 29 deletions(-)

diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
index 00ce0e5bb970..3f29dd28bd43 100644
--- a/drivers/mtd/nand/raw/meson_nand.c
+++ b/drivers/mtd/nand/raw/meson_nand.c
@@ -35,6 +35,7 @@
 #define NFC_CMD_RB		BIT(20)
 #define NFC_CMD_SCRAMBLER_ENABLE	BIT(19)
 #define NFC_CMD_SCRAMBLER_DISABLE	0
+#define NFC_CMD_SHORTMODE_ENABLE	1
 #define NFC_CMD_SHORTMODE_DISABLE	0
 #define NFC_CMD_RB_INT		BIT(14)
 #define NFC_CMD_RB_INT_NO_PIN	((0xb << 10) | BIT(18) | BIT(16))
@@ -78,6 +79,8 @@
 #define DMA_DIR(dir)		((dir) ? NFC_CMD_N2M : NFC_CMD_M2N)
 #define DMA_ADDR_ALIGN		8
 
+#define NFC_SHORT_MODE_ECC_SZ	384
+
 #define ECC_CHECK_RETURN_FF	(-1)
 
 #define NAND_CE0		(0xe << 10)
@@ -125,6 +128,8 @@ struct meson_nfc_nand_chip {
 	u32 twb;
 	u32 tadl;
 	u32 tbers_max;
+	u32 boot_page_last;
+	u32 boot_page_step;
 
 	u32 bch_mode;
 	u8 *data_buf;
@@ -298,28 +303,49 @@ static void meson_nfc_cmd_seed(struct meson_nfc *nfc, u32 seed)
 	       nfc->reg_base + NFC_REG_CMD);
 }
 
-static void meson_nfc_cmd_access(struct nand_chip *nand, int raw, bool dir,
-				 int scrambler)
+static int meson_nfc_page_is_boot(struct nand_chip *nand, int page)
+{
+	const struct meson_nfc_nand_chip *meson_chip = to_meson_nand(nand);
+
+	return (nand->options & NAND_IS_BOOT_MEDIUM) &&
+	       !(page % meson_chip->boot_page_step) &&
+	       (page < meson_chip->boot_page_last);
+}
+
+static void meson_nfc_cmd_access(struct nand_chip *nand, bool raw, bool dir, int page)
 {
+	const struct meson_nfc_nand_chip *meson_chip = to_meson_nand(nand);
 	struct mtd_info *mtd = nand_to_mtd(nand);
 	struct meson_nfc *nfc = nand_get_controller_data(mtd_to_nand(mtd));
-	struct meson_nfc_nand_chip *meson_chip = to_meson_nand(nand);
-	u32 bch = meson_chip->bch_mode, cmd;
 	int len = mtd->writesize, pagesize, pages;
+	int scrambler;
+	u32 cmd;
 
-	pagesize = nand->ecc.size;
+	if (nand->options & NAND_NEED_SCRAMBLING)
+		scrambler = NFC_CMD_SCRAMBLER_ENABLE;
+	else
+		scrambler = NFC_CMD_SCRAMBLER_DISABLE;
 
 	if (raw) {
 		len = mtd->writesize + mtd->oobsize;
 		cmd = len | scrambler | DMA_DIR(dir);
-		writel(cmd, nfc->reg_base + NFC_REG_CMD);
-		return;
-	}
+	} else if (meson_nfc_page_is_boot(nand, page)) {
+		pagesize = NFC_SHORT_MODE_ECC_SZ >> 3;
+		pages = mtd->writesize / 512;
+
+		scrambler = NFC_CMD_SCRAMBLER_ENABLE;
+		cmd = CMDRWGEN(DMA_DIR(dir), scrambler, NFC_ECC_BCH8_1K,
+			       NFC_CMD_SHORTMODE_ENABLE, pagesize, pages);
+	} else {
+		pagesize = nand->ecc.size >> 3;
+		pages = len / nand->ecc.size;
 
-	pages = len / nand->ecc.size;
+		cmd = CMDRWGEN(DMA_DIR(dir), scrambler, meson_chip->bch_mode,
+			       NFC_CMD_SHORTMODE_DISABLE, pagesize, pages);
+	}
 
-	cmd = CMDRWGEN(DMA_DIR(dir), scrambler, bch,
-		       NFC_CMD_SHORTMODE_DISABLE, pagesize, pages);
+	if (scrambler == NFC_CMD_SCRAMBLER_ENABLE)
+		meson_nfc_cmd_seed(nfc, page);
 
 	writel(cmd, nfc->reg_base + NFC_REG_CMD);
 }
@@ -743,15 +769,7 @@ static int meson_nfc_write_page_sub(struct nand_chip *nand,
 	if (ret)
 		return ret;
 
-	if (nand->options & NAND_NEED_SCRAMBLING) {
-		meson_nfc_cmd_seed(nfc, page);
-		meson_nfc_cmd_access(nand, raw, DIRWRITE,
-				     NFC_CMD_SCRAMBLER_ENABLE);
-	} else {
-		meson_nfc_cmd_access(nand, raw, DIRWRITE,
-				     NFC_CMD_SCRAMBLER_DISABLE);
-	}
-
+	meson_nfc_cmd_access(nand, raw, DIRWRITE, page);
 	cmd = nfc->param.chip_select | NFC_CMD_CLE | NAND_CMD_PAGEPROG;
 	writel(cmd, nfc->reg_base + NFC_REG_CMD);
 	meson_nfc_queue_rb(nand, PSEC_TO_MSEC(sdr->tPROG_max), false);
@@ -829,15 +847,7 @@ static int meson_nfc_read_page_sub(struct nand_chip *nand,
 	if (ret)
 		return ret;
 
-	if (nand->options & NAND_NEED_SCRAMBLING) {
-		meson_nfc_cmd_seed(nfc, page);
-		meson_nfc_cmd_access(nand, raw, DIRREAD,
-				     NFC_CMD_SCRAMBLER_ENABLE);
-	} else {
-		meson_nfc_cmd_access(nand, raw, DIRREAD,
-				     NFC_CMD_SCRAMBLER_DISABLE);
-	}
-
+	meson_nfc_cmd_access(nand, raw, DIRREAD, page);
 	ret = meson_nfc_wait_dma_finish(nfc);
 	meson_nfc_check_ecc_pages_valid(nfc, nand, raw);
 
@@ -1436,6 +1446,26 @@ meson_nfc_nand_chip_init(struct device *dev,
 	if (ret)
 		return ret;
 
+	if (nand->options & NAND_IS_BOOT_MEDIUM) {
+		ret = of_property_read_u32(np, "meson,boot-page-last",
+					   &meson_chip->boot_page_last);
+		if (ret) {
+			dev_err(dev, "could not retrieve 'meson,boot-page-last' property: %d",
+				ret);
+			nand_cleanup(nand);
+			return ret;
+		}
+
+		ret = of_property_read_u32(np, "meson,boot-page-step",
+					   &meson_chip->boot_page_step);
+		if (ret) {
+			dev_err(dev, "could not retrieve 'meson,boot-page-step' property: %d",
+				ret);
+			nand_cleanup(nand);
+			return ret;
+		}
+	}
+
 	ret = mtd_device_register(mtd, NULL, 0);
 	if (ret) {
 		dev_err(dev, "failed to register MTD device: %d\n", ret);
-- 
2.35.0