mtd: mxc_nand: add support for multiple chips on V21 devices

Do the following to add support for up to 4 chips on V21 devices (i.MX25 and
i.MX35):

* implement .select_chip for V21
* adjust existing NFC_V1_V2_BUF_ADDR writes to take chip select into account
* unlock all chip selects at preset_v1_v2()
* scan up to 4 devices at .probe

This has been tested on i.MX25 with two attached NAND chip (on one die).
Signed-off-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/mxc_nand.c

@@ -56,8 +56,14 @@
 #define NFC_V1_V2_WRPROT		(host->regs + 0x12)
 #define NFC_V1_UNLOCKSTART_BLKADDR	(host->regs + 0x14)
 #define NFC_V1_UNLOCKEND_BLKADDR	(host->regs + 0x16)
-#define NFC_V21_UNLOCKSTART_BLKADDR	(host->regs + 0x20)
-#define NFC_V21_UNLOCKEND_BLKADDR	(host->regs + 0x22)
+#define NFC_V21_UNLOCKSTART_BLKADDR0	(host->regs + 0x20)
+#define NFC_V21_UNLOCKSTART_BLKADDR1	(host->regs + 0x24)
+#define NFC_V21_UNLOCKSTART_BLKADDR2	(host->regs + 0x28)
+#define NFC_V21_UNLOCKSTART_BLKADDR3	(host->regs + 0x2c)
+#define NFC_V21_UNLOCKEND_BLKADDR0	(host->regs + 0x22)
+#define NFC_V21_UNLOCKEND_BLKADDR1	(host->regs + 0x26)
+#define NFC_V21_UNLOCKEND_BLKADDR2	(host->regs + 0x2a)
+#define NFC_V21_UNLOCKEND_BLKADDR3	(host->regs + 0x2e)
 #define NFC_V1_V2_NF_WRPRST		(host->regs + 0x18)
 #define NFC_V1_V2_CONFIG1		(host->regs + 0x1a)
 #define NFC_V1_V2_CONFIG2		(host->regs + 0x1c)
@@ -152,6 +158,7 @@ struct mxc_nand_host {
 	int			clk_act;
 	int			irq;
 	int			eccsize;
+	int			active_cs;
 
 	struct completion	op_completion;
 
@@ -445,7 +452,7 @@ static void send_page_v1_v2(struct mtd_info *mtd, unsigned int ops)
 	for (i = 0; i < bufs; i++) {
 
 		/* NANDFC buffer 0 is used for page read/write */
-		writew(i, NFC_V1_V2_BUF_ADDR);
+		writew((host->active_cs << 4) | i, NFC_V1_V2_BUF_ADDR);
 
 		writew(ops, NFC_V1_V2_CONFIG2);
 
@@ -470,7 +477,7 @@ static void send_read_id_v1_v2(struct mxc_nand_host *host)
 	struct nand_chip *this = &host->nand;
 
 	/* NANDFC buffer 0 is used for device ID output */
-	writew(0x0, NFC_V1_V2_BUF_ADDR);
+	writew(host->active_cs << 4, NFC_V1_V2_BUF_ADDR);
 
 	writew(NFC_ID, NFC_V1_V2_CONFIG2);
 
@@ -505,7 +512,7 @@ static uint16_t get_dev_status_v1_v2(struct mxc_nand_host *host)
 	uint32_t store;
 	uint16_t ret;
 
-	writew(0x0, NFC_V1_V2_BUF_ADDR);
+	writew(host->active_cs << 4, NFC_V1_V2_BUF_ADDR);
 
 	/*
 	 * The device status is stored in main_area0. To
@@ -686,24 +693,24 @@ static void mxc_nand_select_chip(struct mtd_info *mtd, int chip)
 	struct nand_chip *nand_chip = mtd->priv;
 	struct mxc_nand_host *host = nand_chip->priv;
 
-	switch (chip) {
-	case -1:
+	if (chip == -1) {
 		/* Disable the NFC clock */
 		if (host->clk_act) {
 			clk_disable(host->clk);
 			host->clk_act = 0;
 		}
-		break;
-	case 0:
+		return;
+	}
+
+	if (!host->clk_act) {
 		/* Enable the NFC clock */
-		if (!host->clk_act) {
-			clk_enable(host->clk);
-			host->clk_act = 1;
-		}
-		break;
+		clk_enable(host->clk);
+		host->clk_act = 1;
+	}
 
-	default:
-		break;
+	if (nfc_is_v21()) {
+		host->active_cs = chip;
+		writew(host->active_cs << 4, NFC_V1_V2_BUF_ADDR);
 	}
 }
 
@@ -834,8 +841,14 @@ static void preset_v1_v2(struct mtd_info *mtd)
 
 	/* Blocks to be unlocked */
 	if (nfc_is_v21()) {
-		writew(0x0, NFC_V21_UNLOCKSTART_BLKADDR);
-		writew(0xffff, NFC_V21_UNLOCKEND_BLKADDR);
+		writew(0x0, NFC_V21_UNLOCKSTART_BLKADDR0);
+		writew(0x0, NFC_V21_UNLOCKSTART_BLKADDR1);
+		writew(0x0, NFC_V21_UNLOCKSTART_BLKADDR2);
+		writew(0x0, NFC_V21_UNLOCKSTART_BLKADDR3);
+		writew(0xffff, NFC_V21_UNLOCKEND_BLKADDR0);
+		writew(0xffff, NFC_V21_UNLOCKEND_BLKADDR1);
+		writew(0xffff, NFC_V21_UNLOCKEND_BLKADDR2);
+		writew(0xffff, NFC_V21_UNLOCKEND_BLKADDR3);
 	} else if (nfc_is_v1()) {
 		writew(0x0, NFC_V1_UNLOCKSTART_BLKADDR);
 		writew(0x4000, NFC_V1_UNLOCKEND_BLKADDR);
@@ -1200,7 +1213,7 @@ static int __init mxcnd_probe(struct platform_device *pdev)
 		irq_control_v1_v2(host, 1);
 
 	/* first scan to find the device and get the page size */
-	if (nand_scan_ident(mtd, 1, NULL)) {
+	if (nand_scan_ident(mtd, nfc_is_v21() ? 4 : 1, NULL)) {
 		err = -ENXIO;
 		goto escan;
 	}