riscv: sifive: fu540: Use OTP DM driver for serial environment variable

Use the OTP DM driver to set the serial environment variable.
Signed-off-by: NPragnesh Patel <pragnesh.patel@sifive.com>
Reviewed-by: NBin Meng <bmeng.cn@gmail.com>
Tested-by: NBin Meng <bmeng.cn@gmail.com>
Reviewed-by: NJagan Teki <jagan@amarulasolutions.com>
Tested-by: NJagan Teki <jagan@amarulasolutions.com>

arch/riscv/dts/fu540-c000-u-boot.dtsi

+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/*
+ * (C) Copyright 2019 SiFive, Inc
+ */
+
+/ {
+	soc {
+		otp: otp@10070000 {
+			compatible = "sifive,fu540-c000-otp";
+			reg = <0x0 0x10070000 0x0 0x0FFF>;
+			fuse-count = <0x1000>;
+		};
+	};
+};

arch/riscv/dts/hifive-unleashed-a00-u-boot.dtsi

@@ -3,6 +3,8 @@
  * Copyright (C) 2019 Jagan Teki <jagan@amarulasolutions.com>
  */
 
+#include "fu540-c000-u-boot.dtsi"
+
 / {
 	aliases {
 		spi0 = &qspi0;

board/sifive/fu540/Kconfig

@@ -51,5 +51,7 @@ config BOARD_SPECIFIC_OPTIONS # dummy
 	imply SIFIVE_GPIO
 	imply CMD_GPIO
 	imply SMP
+	imply MISC
+	imply SIFIVE_OTP
 
 endif

board/sifive/fu540/fu540.c

@@ -6,101 +6,68 @@
  *   Anup Patel <anup.patel@wdc.com>
  */
 
-#include <common.h>
 #include <dm.h>
 #include <env.h>
 #include <init.h>
+#include <log.h>
 #include <linux/bug.h>
 #include <linux/delay.h>
 #include <linux/io.h>
+#include <misc.h>
+
+/*
+ * This define is a value used for error/unknown serial.
+ * If we really care about distinguishing errors and 0 is
+ * valid, we'll need a different one.
+ */
+#define ERROR_READING_SERIAL_NUMBER       0
 
 #ifdef CONFIG_MISC_INIT_R
 
-#define FU540_OTP_BASE_ADDR			0x10070000
-
-struct fu540_otp_regs {
-	u32 pa;     /* Address input */
-	u32 paio;   /* Program address input */
-	u32 pas;    /* Program redundancy cell selection input */
-	u32 pce;    /* OTP Macro enable input */
-	u32 pclk;   /* Clock input */
-	u32 pdin;   /* Write data input */
-	u32 pdout;  /* Read data output */
-	u32 pdstb;  /* Deep standby mode enable input (active low) */
-	u32 pprog;  /* Program mode enable input */
-	u32 ptc;    /* Test column enable input */
-	u32 ptm;    /* Test mode enable input */
-	u32 ptm_rep;/* Repair function test mode enable input */
-	u32 ptr;    /* Test row enable input */
-	u32 ptrim;  /* Repair function enable input */
-	u32 pwe;    /* Write enable input (defines program cycle) */
-} __packed;
-
-#define BYTES_PER_FUSE				4
-#define NUM_FUSES				0x1000
-
-static int fu540_otp_read(int offset, void *buf, int size)
+#if CONFIG_IS_ENABLED(SIFIVE_OTP)
+static u32 otp_read_serialnum(struct udevice *dev)
 {
-	struct fu540_otp_regs *regs = (void __iomem *)FU540_OTP_BASE_ADDR;
-	unsigned int i;
-	int fuseidx = offset / BYTES_PER_FUSE;
-	int fusecount = size / BYTES_PER_FUSE;
-	u32 fusebuf[fusecount];
-
-	/* check bounds */
-	if (offset < 0 || size < 0)
-		return -EINVAL;
-	if (fuseidx >= NUM_FUSES)
-		return -EINVAL;
-	if ((fuseidx + fusecount) > NUM_FUSES)
-		return -EINVAL;
+	int ret;
+	u32 serial[2] = {0};
 
-	/* init OTP */
-	writel(0x01, &regs->pdstb); /* wake up from stand-by */
-	writel(0x01, &regs->ptrim); /* enable repair function */
-	writel(0x01, &regs->pce);   /* enable input */
-
-	/* read all requested fuses */
-	for (i = 0; i < fusecount; i++, fuseidx++) {
-		writel(fuseidx, &regs->pa);
-
-		/* cycle clock to read */
-		writel(0x01, &regs->pclk);
-		mdelay(1);
-		writel(0x00, &regs->pclk);
-		mdelay(1);
-
-		/* read the value */
-		fusebuf[i] = readl(&regs->pdout);
-	}
+	for (int i = 0xfe * 4; i > 0; i -= 8) {
+		ret = misc_read(dev, i, serial, sizeof(serial));
 
-	/* shut down */
-	writel(0, &regs->pce);
-	writel(0, &regs->ptrim);
-	writel(0, &regs->pdstb);
+		if (ret != sizeof(serial)) {
+			printf("%s: error reading serial from OTP\n", __func__);
+			break;
+		}
 
-	/* copy out */
-	memcpy(buf, fusebuf, size);
+		if (serial[0] == ~serial[1])
+			return serial[0];
+	}
 
-	return 0;
+	return ERROR_READING_SERIAL_NUMBER;
 }
+#endif
 
 static u32 fu540_read_serialnum(void)
 {
+	u32 serial = ERROR_READING_SERIAL_NUMBER;
+
+#if CONFIG_IS_ENABLED(SIFIVE_OTP)
+	struct udevice *dev;
 	int ret;
-	u32 serial[2] = {0};
 
-	for (int i = 0xfe * 4; i > 0; i -= 8) {
-		ret = fu540_otp_read(i, serial, sizeof(serial));
-		if (ret) {
-			printf("%s: error reading from OTP\n", __func__);
-			break;
-		}
-		if (serial[0] == ~serial[1])
-			return serial[0];
+	/* init OTP */
+	ret = uclass_get_device_by_driver(UCLASS_MISC,
+					  DM_GET_DRIVER(sifive_otp), &dev);
+
+	if (ret) {
+		debug("%s: could not find otp device\n", __func__);
+		return serial;
 	}
 
-	return 0;
+	/* read serial from OTP and set env var */
+	serial = otp_read_serialnum(dev);
+#endif
+
+	return serial;
 }
 
 static void fu540_setup_macaddr(u32 serialnum)