nvmem: Add the Broadcom OTP controller driver

Add support for 32 and 64-bit versions of Broadcom's On-Chip OTP
controller. These controllers are used on SoC's such as Cygnus and
Stingray.
Reviewed-by: Ray Jui <ray.jui@broadcom.com>
Tested-by: Jonathan Richardson <jonathan.richardson@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Oza Pawandeep <oza@broadcom.com>
Signed-off-by: Jonathan Richardson <jonathan.richardson@broadcom.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/nvmem/Kconfig

@@ -90,6 +90,18 @@ config ROCKCHIP_EFUSE
 	  This driver can also be built as a module. If so, the module
 	  will be called nvmem_rockchip_efuse.
 
+config NVMEM_BCM_OCOTP
+	tristate "Broadcom On-Chip OTP Controller support"
+	depends on ARCH_BCM_IPROC || COMPILE_TEST
+	depends on HAS_IOMEM
+	default ARCH_BCM_IPROC
+	help
+	  Say y here to enable read/write access to the Broadcom OTP
+	  controller.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called nvmem-bcm-ocotp.
+
 config NVMEM_SUNXI_SID
 	tristate "Allwinner SoCs SID support"
 	depends on ARCH_SUNXI

drivers/nvmem/Makefile

@@ -6,6 +6,8 @@ obj-$(CONFIG_NVMEM)		+= nvmem_core.o
 nvmem_core-y			:= core.o
 
 # Devices
+obj-$(CONFIG_NVMEM_BCM_OCOTP)	+= nvmem-bcm-ocotp.o
+nvmem-bcm-ocotp-y		:= bcm-ocotp.o
 obj-$(CONFIG_NVMEM_IMX_OCOTP)	+= nvmem-imx-ocotp.o
 nvmem-imx-ocotp-y		:= imx-ocotp.o
 obj-$(CONFIG_NVMEM_LPC18XX_EEPROM)	+= nvmem_lpc18xx_eeprom.o

drivers/nvmem/bcm-ocotp.c

+/*
+ * Copyright (C) 2016 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+
+/*
+ * # of tries for OTP Status. The time to execute a command varies. The slowest
+ * commands are writes which also vary based on the # of bits turned on. Writing
+ * 0xffffffff takes ~3800 us.
+ */
+#define OTPC_RETRIES                 5000
+
+/* Sequence to enable OTP program */
+#define OTPC_PROG_EN_SEQ             { 0xf, 0x4, 0x8, 0xd }
+
+/* OTPC Commands */
+#define OTPC_CMD_READ                0x0
+#define OTPC_CMD_OTP_PROG_ENABLE     0x2
+#define OTPC_CMD_OTP_PROG_DISABLE    0x3
+#define OTPC_CMD_PROGRAM             0xA
+
+/* OTPC Status Bits */
+#define OTPC_STAT_CMD_DONE           BIT(1)
+#define OTPC_STAT_PROG_OK            BIT(2)
+
+/* OTPC register definition */
+#define OTPC_MODE_REG_OFFSET         0x0
+#define OTPC_MODE_REG_OTPC_MODE      0
+#define OTPC_COMMAND_OFFSET          0x4
+#define OTPC_COMMAND_COMMAND_WIDTH   6
+#define OTPC_CMD_START_OFFSET        0x8
+#define OTPC_CMD_START_START         0
+#define OTPC_CPU_STATUS_OFFSET       0xc
+#define OTPC_CPUADDR_REG_OFFSET      0x28
+#define OTPC_CPUADDR_REG_OTPC_CPU_ADDRESS_WIDTH 16
+#define OTPC_CPU_WRITE_REG_OFFSET    0x2c
+
+#define OTPC_CMD_MASK  (BIT(OTPC_COMMAND_COMMAND_WIDTH) - 1)
+#define OTPC_ADDR_MASK (BIT(OTPC_CPUADDR_REG_OTPC_CPU_ADDRESS_WIDTH) - 1)
+
+
+struct otpc_map {
+	/* in words. */
+	u32 otpc_row_size;
+	/* 128 bit row / 4 words support. */
+	u16 data_r_offset[4];
+	/* 128 bit row / 4 words support. */
+	u16 data_w_offset[4];
+};
+
+static struct otpc_map otp_map = {
+	.otpc_row_size = 1,
+	.data_r_offset = {0x10},
+	.data_w_offset = {0x2c},
+};
+
+static struct otpc_map otp_map_v2 = {
+	.otpc_row_size = 2,
+	.data_r_offset = {0x10, 0x5c},
+	.data_w_offset = {0x2c, 0x64},
+};
+
+struct otpc_priv {
+	struct device       *dev;
+	void __iomem        *base;
+	struct otpc_map     *map;
+	struct nvmem_config *config;
+};
+
+static inline void set_command(void __iomem *base, u32 command)
+{
+	writel(command & OTPC_CMD_MASK, base + OTPC_COMMAND_OFFSET);
+}
+
+static inline void set_cpu_address(void __iomem *base, u32 addr)
+{
+	writel(addr & OTPC_ADDR_MASK, base + OTPC_CPUADDR_REG_OFFSET);
+}
+
+static inline void set_start_bit(void __iomem *base)
+{
+	writel(1 << OTPC_CMD_START_START, base + OTPC_CMD_START_OFFSET);
+}
+
+static inline void reset_start_bit(void __iomem *base)
+{
+	writel(0, base + OTPC_CMD_START_OFFSET);
+}
+
+static inline void write_cpu_data(void __iomem *base, u32 value)
+{
+	writel(value, base + OTPC_CPU_WRITE_REG_OFFSET);
+}
+
+static int poll_cpu_status(void __iomem *base, u32 value)
+{
+	u32 status;
+	u32 retries;
+
+	for (retries = 0; retries < OTPC_RETRIES; retries++) {
+		status = readl(base + OTPC_CPU_STATUS_OFFSET);
+		if (status & value)
+			break;
+		udelay(1);
+	}
+	if (retries == OTPC_RETRIES)
+		return -EAGAIN;
+
+	return 0;
+}
+
+static int enable_ocotp_program(void __iomem *base)
+{
+	static const u32 vals[] = OTPC_PROG_EN_SEQ;
+	int i;
+	int ret;
+
+	/* Write the magic sequence to enable programming */
+	set_command(base, OTPC_CMD_OTP_PROG_ENABLE);
+	for (i = 0; i < ARRAY_SIZE(vals); i++) {
+		write_cpu_data(base, vals[i]);
+		set_start_bit(base);
+		ret = poll_cpu_status(base, OTPC_STAT_CMD_DONE);
+		reset_start_bit(base);
+		if (ret)
+			return ret;
+	}
+
+	return poll_cpu_status(base, OTPC_STAT_PROG_OK);
+}
+
+static int disable_ocotp_program(void __iomem *base)
+{
+	int ret;
+
+	set_command(base, OTPC_CMD_OTP_PROG_DISABLE);
+	set_start_bit(base);
+	ret = poll_cpu_status(base, OTPC_STAT_PROG_OK);
+	reset_start_bit(base);
+
+	return ret;
+}
+
+static int bcm_otpc_read(void *context, unsigned int offset, void *val,
+	size_t bytes)
+{
+	struct otpc_priv *priv = context;
+	u32 *buf = val;
+	u32 bytes_read;
+	u32 address = offset / priv->config->word_size;
+	int i, ret;
+
+	for (bytes_read = 0; bytes_read < bytes;) {
+		set_command(priv->base, OTPC_CMD_READ);
+		set_cpu_address(priv->base, address++);
+		set_start_bit(priv->base);
+		ret = poll_cpu_status(priv->base, OTPC_STAT_CMD_DONE);
+		if (ret) {
+			dev_err(priv->dev, "otp read error: 0x%x", ret);
+			return -EIO;
+		}
+
+		for (i = 0; i < priv->map->otpc_row_size; i++) {
+			*buf++ = readl(priv->base +
+					priv->map->data_r_offset[i]);
+			bytes_read += sizeof(*buf);
+		}
+
+		reset_start_bit(priv->base);
+	}
+
+	return 0;
+}
+
+static int bcm_otpc_write(void *context, unsigned int offset, void *val,
+	size_t bytes)
+{
+	struct otpc_priv *priv = context;
+	u32 *buf = val;
+	u32 bytes_written;
+	u32 address = offset / priv->config->word_size;
+	int i, ret;
+
+	if (offset % priv->config->word_size)
+		return -EINVAL;
+
+	ret = enable_ocotp_program(priv->base);
+	if (ret)
+		return -EIO;
+
+	for (bytes_written = 0; bytes_written < bytes;) {
+		set_command(priv->base, OTPC_CMD_PROGRAM);
+		set_cpu_address(priv->base, address++);
+		for (i = 0; i < priv->map->otpc_row_size; i++) {
+			writel(*buf, priv->base + priv->map->data_r_offset[i]);
+			buf++;
+			bytes_written += sizeof(*buf);
+		}
+		set_start_bit(priv->base);
+		ret = poll_cpu_status(priv->base, OTPC_STAT_CMD_DONE);
+		reset_start_bit(priv->base);
+		if (ret) {
+			dev_err(priv->dev, "otp write error: 0x%x", ret);
+			return -EIO;
+		}
+	}
+
+	disable_ocotp_program(priv->base);
+
+	return 0;
+}
+
+static struct nvmem_config bcm_otpc_nvmem_config = {
+	.name = "bcm-ocotp",
+	.read_only = false,
+	.word_size = 4,
+	.stride = 4,
+	.owner = THIS_MODULE,
+	.reg_read = bcm_otpc_read,
+	.reg_write = bcm_otpc_write,
+};
+
+static const struct of_device_id bcm_otpc_dt_ids[] = {
+	{ .compatible = "brcm,ocotp" },
+	{ .compatible = "brcm,ocotp-v2" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, bcm_otpc_dt_ids);
+
+static int bcm_otpc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *dn = dev->of_node;
+	struct resource *res;
+	struct otpc_priv *priv;
+	struct nvmem_device *nvmem;
+	int err;
+	u32 num_words;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	if (of_device_is_compatible(dev->of_node, "brcm,ocotp"))
+		priv->map = &otp_map;
+	else if (of_device_is_compatible(dev->of_node, "brcm,ocotp-v2"))
+		priv->map = &otp_map_v2;
+	else {
+		dev_err(&pdev->dev,
+			"%s otpc config map not defined\n", __func__);
+		return -EINVAL;
+	}
+
+	/* Get OTP base address register. */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(priv->base)) {
+		dev_err(dev, "unable to map I/O memory\n");
+		return PTR_ERR(priv->base);
+	}
+
+	/* Enable CPU access to OTPC. */
+	writel(readl(priv->base + OTPC_MODE_REG_OFFSET) |
+		BIT(OTPC_MODE_REG_OTPC_MODE),
+		priv->base + OTPC_MODE_REG_OFFSET);
+	reset_start_bit(priv->base);
+
+	/* Read size of memory in words. */
+	err = of_property_read_u32(dn, "brcm,ocotp-size", &num_words);
+	if (err) {
+		dev_err(dev, "size parameter not specified\n");
+		return -EINVAL;
+	} else if (num_words == 0) {
+		dev_err(dev, "size must be > 0\n");
+		return -EINVAL;
+	}
+
+	bcm_otpc_nvmem_config.size = 4 * num_words;
+	bcm_otpc_nvmem_config.dev = dev;
+	bcm_otpc_nvmem_config.priv = priv;
+
+	if (of_device_is_compatible(dev->of_node, "brcm,ocotp-v2")) {
+		bcm_otpc_nvmem_config.word_size = 8;
+		bcm_otpc_nvmem_config.stride = 8;
+	}
+
+	priv->config = &bcm_otpc_nvmem_config;
+
+	nvmem = nvmem_register(&bcm_otpc_nvmem_config);
+	if (IS_ERR(nvmem)) {
+		dev_err(dev, "error registering nvmem config\n");
+		return PTR_ERR(nvmem);
+	}
+
+	platform_set_drvdata(pdev, nvmem);
+
+	return 0;
+}
+
+static int bcm_otpc_remove(struct platform_device *pdev)
+{
+	struct nvmem_device *nvmem = platform_get_drvdata(pdev);
+
+	return nvmem_unregister(nvmem);
+}
+
+static struct platform_driver bcm_otpc_driver = {
+	.probe	= bcm_otpc_probe,
+	.remove	= bcm_otpc_remove,
+	.driver = {
+		.name	= "brcm-otpc",
+		.of_match_table = bcm_otpc_dt_ids,
+	},
+};
+module_platform_driver(bcm_otpc_driver);
+
+MODULE_DESCRIPTION("Broadcom OTPC driver");
+MODULE_LICENSE("GPL v2");