nvmem: Add Vybrid OCOTP support

The patch adds support for the On Chip One Time Programmable Peripheral
(OCOTP) on the Vybrid platform.

Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/nvmem/Kconfig

@@ -36,4 +36,14 @@ config NVMEM_SUNXI_SID
 	  This driver can also be built as a module. If so, the module
 	  will be called nvmem_sunxi_sid.
 
+config NVMEM_VF610_OCOTP
+	tristate "VF610 SoC OCOTP support"
+	depends on SOC_VF610 || COMPILE_TEST
+	help
+	  This is a driver for the 'OCOTP' peripheral available on Vybrid
+	  devices like VF5xx and VF6xx.
+
+	  This driver can also be build as a module. If so, the module will
+	  be called nvmem-vf610-ocotp.
+
 endif

drivers/nvmem/Makefile

@@ -10,3 +10,5 @@ obj-$(CONFIG_QCOM_QFPROM)	+= nvmem_qfprom.o
 nvmem_qfprom-y			:= qfprom.o
 obj-$(CONFIG_NVMEM_SUNXI_SID)	+= nvmem_sunxi_sid.o
 nvmem_sunxi_sid-y		:= sunxi_sid.o
+obj-$(CONFIG_NVMEM_VF610_OCOTP)	+= nvmem-vf610-ocotp.o
+nvmem-vf610-ocotp-y		:= vf610-ocotp.o

drivers/nvmem/vf610-ocotp.c

@@ -0,0 +1,302 @@
+/*
+ * Copyright (C) 2015 Toradex AG.
+ *
+ * Author: Sanchayan Maity <sanchayan.maity@toradex.com>
+ *
+ * Based on the barebox ocotp driver,
+ * Copyright (c) 2010 Baruch Siach <baruch@tkos.co.il>
+ *	Orex Computed Radiography
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#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/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+/* OCOTP Register Offsets */
+#define OCOTP_CTRL_REG				0x00
+#define OCOTP_CTRL_SET				0x04
+#define OCOTP_CTRL_CLR				0x08
+#define OCOTP_TIMING				0x10
+#define OCOTP_DATA				0x20
+#define OCOTP_READ_CTRL_REG			0x30
+#define OCOTP_READ_FUSE_DATA			0x40
+
+/* OCOTP Register bits and masks */
+#define OCOTP_CTRL_WR_UNLOCK			16
+#define OCOTP_CTRL_WR_UNLOCK_KEY		0x3E77
+#define OCOTP_CTRL_WR_UNLOCK_MASK		GENMASK(31, 16)
+#define OCOTP_CTRL_ADDR				0
+#define OCOTP_CTRL_ADDR_MASK			GENMASK(6, 0)
+#define OCOTP_CTRL_RELOAD_SHADOWS		BIT(10)
+#define OCOTP_CTRL_ERR				BIT(9)
+#define OCOTP_CTRL_BUSY				BIT(8)
+
+#define OCOTP_TIMING_STROBE_READ		16
+#define OCOTP_TIMING_STROBE_READ_MASK		GENMASK(21, 16)
+#define OCOTP_TIMING_RELAX			12
+#define OCOTP_TIMING_RELAX_MASK			GENMASK(15, 12)
+#define OCOTP_TIMING_STROBE_PROG		0
+#define OCOTP_TIMING_STROBE_PROG_MASK		GENMASK(11, 0)
+
+#define OCOTP_READ_CTRL_READ_FUSE		0x1
+
+#define VF610_OCOTP_TIMEOUT			100000
+
+#define BF(value, field)		(((value) << field) & field##_MASK)
+
+#define DEF_RELAX				20
+
+static const int base_to_fuse_addr_mappings[][2] = {
+	{0x400, 0x00},
+	{0x410, 0x01},
+	{0x420, 0x02},
+	{0x450, 0x05},
+	{0x4F0, 0x0F},
+	{0x600, 0x20},
+	{0x610, 0x21},
+	{0x620, 0x22},
+	{0x630, 0x23},
+	{0x640, 0x24},
+	{0x650, 0x25},
+	{0x660, 0x26},
+	{0x670, 0x27},
+	{0x6F0, 0x2F},
+	{0x880, 0x38},
+	{0x890, 0x39},
+	{0x8A0, 0x3A},
+	{0x8B0, 0x3B},
+	{0x8C0, 0x3C},
+	{0x8D0, 0x3D},
+	{0x8E0, 0x3E},
+	{0x8F0, 0x3F},
+	{0xC80, 0x78},
+	{0xC90, 0x79},
+	{0xCA0, 0x7A},
+	{0xCB0, 0x7B},
+	{0xCC0, 0x7C},
+	{0xCD0, 0x7D},
+	{0xCE0, 0x7E},
+	{0xCF0, 0x7F},
+};
+
+struct vf610_ocotp {
+	void __iomem *base;
+	struct clk *clk;
+	struct device *dev;
+	struct nvmem_device *nvmem;
+	int timing;
+};
+
+static int vf610_ocotp_wait_busy(void __iomem *base)
+{
+	int timeout = VF610_OCOTP_TIMEOUT;
+
+	while ((readl(base) & OCOTP_CTRL_BUSY) && --timeout)
+		udelay(10);
+
+	if (!timeout) {
+		writel(OCOTP_CTRL_ERR, base + OCOTP_CTRL_CLR);
+		return -ETIMEDOUT;
+	}
+
+	udelay(10);
+
+	return 0;
+}
+
+static int vf610_ocotp_calculate_timing(struct vf610_ocotp *ocotp_dev)
+{
+	u32 clk_rate;
+	u32 relax, strobe_read, strobe_prog;
+	u32 timing;
+
+	clk_rate = clk_get_rate(ocotp_dev->clk);
+
+	/* Refer section OTP read/write timing parameters in TRM */
+	relax = clk_rate / (1000000000 / DEF_RELAX) - 1;
+	strobe_prog = clk_rate / (1000000000 / 10000) + 2 * (DEF_RELAX + 1) - 1;
+	strobe_read = clk_rate / (1000000000 / 40) + 2 * (DEF_RELAX + 1) - 1;
+
+	timing = BF(relax, OCOTP_TIMING_RELAX);
+	timing |= BF(strobe_read, OCOTP_TIMING_STROBE_READ);
+	timing |= BF(strobe_prog, OCOTP_TIMING_STROBE_PROG);
+
+	return timing;
+}
+
+static int vf610_get_fuse_address(int base_addr_offset)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(base_to_fuse_addr_mappings); i++) {
+		if (base_to_fuse_addr_mappings[i][0] == base_addr_offset)
+			return base_to_fuse_addr_mappings[i][1];
+	}
+
+	return -EINVAL;
+}
+
+static int vf610_ocotp_write(void *context, const void *data, size_t count)
+{
+	return 0;
+}
+
+static int vf610_ocotp_read(void *context,
+			const void *off, size_t reg_size,
+			void *val, size_t val_size)
+{
+	struct vf610_ocotp *ocotp = context;
+	void __iomem *base = ocotp->base;
+	unsigned int offset = *(u32 *)off;
+	u32 reg, *buf = val;
+	int fuse_addr;
+	int ret;
+
+	while (val_size > 0) {
+		fuse_addr = vf610_get_fuse_address(offset);
+		if (fuse_addr > 0) {
+			writel(ocotp->timing, base + OCOTP_TIMING);
+			ret = vf610_ocotp_wait_busy(base + OCOTP_CTRL_REG);
+			if (ret)
+				return ret;
+
+			reg = readl(base + OCOTP_CTRL_REG);
+			reg &= ~OCOTP_CTRL_ADDR_MASK;
+			reg &= ~OCOTP_CTRL_WR_UNLOCK_MASK;
+			reg |= BF(fuse_addr, OCOTP_CTRL_ADDR);
+			writel(reg, base + OCOTP_CTRL_REG);
+
+			writel(OCOTP_READ_CTRL_READ_FUSE,
+				base + OCOTP_READ_CTRL_REG);
+			ret = vf610_ocotp_wait_busy(base + OCOTP_CTRL_REG);
+			if (ret)
+				return ret;
+
+			if (readl(base) & OCOTP_CTRL_ERR) {
+				dev_dbg(ocotp->dev, "Error reading from fuse address %x\n",
+					fuse_addr);
+				writel(OCOTP_CTRL_ERR, base + OCOTP_CTRL_CLR);
+			}
+
+			/*
+			 * In case of error, we do not abort and expect to read
+			 * 0xBADABADA as mentioned by the TRM. We just read this
+			 * value and return.
+			 */
+			*buf = readl(base + OCOTP_READ_FUSE_DATA);
+		} else {
+			*buf = 0;
+		}
+
+		buf++;
+		val_size--;
+		offset += reg_size;
+	}
+
+	return 0;
+}
+
+static struct regmap_bus vf610_ocotp_bus = {
+	.read = vf610_ocotp_read,
+	.write = vf610_ocotp_write,
+	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
+	.val_format_endian_default = REGMAP_ENDIAN_NATIVE,
+};
+
+static struct regmap_config ocotp_regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4,
+};
+
+static struct nvmem_config ocotp_config = {
+	.name = "ocotp",
+	.owner = THIS_MODULE,
+};
+
+static const struct of_device_id ocotp_of_match[] = {
+	{ .compatible = "fsl,vf610-ocotp", },
+	{/* sentinel */},
+};
+MODULE_DEVICE_TABLE(of, ocotp_of_match);
+
+static int vf610_ocotp_remove(struct platform_device *pdev)
+{
+	struct vf610_ocotp *ocotp_dev = platform_get_drvdata(pdev);
+
+	return nvmem_unregister(ocotp_dev->nvmem);
+}
+
+static int vf610_ocotp_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	struct regmap *regmap;
+	struct vf610_ocotp *ocotp_dev;
+
+	ocotp_dev = devm_kzalloc(&pdev->dev,
+			sizeof(struct vf610_ocotp), GFP_KERNEL);
+	if (!ocotp_dev)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	ocotp_dev->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(ocotp_dev->base))
+		return PTR_ERR(ocotp_dev->base);
+
+	ocotp_dev->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(ocotp_dev->clk)) {
+		dev_err(dev, "failed getting clock, err = %ld\n",
+			PTR_ERR(ocotp_dev->clk));
+		return PTR_ERR(ocotp_dev->clk);
+	}
+
+	ocotp_regmap_config.max_register = resource_size(res);
+	regmap = devm_regmap_init(dev,
+		&vf610_ocotp_bus, ocotp_dev, &ocotp_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(dev, "regmap init failed\n");
+		return PTR_ERR(regmap);
+	}
+	ocotp_config.dev = dev;
+
+	ocotp_dev->nvmem = nvmem_register(&ocotp_config);
+	if (IS_ERR(ocotp_dev->nvmem))
+		return PTR_ERR(ocotp_dev->nvmem);
+
+	ocotp_dev->dev = dev;
+	platform_set_drvdata(pdev, ocotp_dev);
+
+	ocotp_dev->timing = vf610_ocotp_calculate_timing(ocotp_dev);
+
+	return 0;
+}
+
+static struct platform_driver vf610_ocotp_driver = {
+	.probe = vf610_ocotp_probe,
+	.remove = vf610_ocotp_remove,
+	.driver = {
+		.name = "vf610-ocotp",
+		.of_match_table = ocotp_of_match,
+	},
+};
+module_platform_driver(vf610_ocotp_driver);
+MODULE_AUTHOR("Sanchayan Maity <sanchayan.maity@toradex.com>");
+MODULE_DESCRIPTION("Vybrid OCOTP driver");
+MODULE_LICENSE("GPL v2");