Re: [PATCH v1 2/3] nvmem: Add the Broadcom OTP controller driver

From: Srinivas Kandagatla
Date: Mon Oct 31 2016 - 10:24:53 EST


On 24/10/16 20:12, Jonathan Richardson wrote:
From: Jonathan Richardson <jonathar@xxxxxxxxxxxx>

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@xxxxxxxxxxxx>
Tested-by: Jonathan Richardson <jonathan.richardson@xxxxxxxxxxxx>
Signed-off-by: Scott Branden <scott.branden@xxxxxxxxxxxx>
Signed-off-by: Oza Pawandeep <oza@xxxxxxxxxxxx>
Signed-off-by: Jonathan Richardson <jonathan.richardson@xxxxxxxxxxxx>
---
drivers/nvmem/Kconfig | 12 ++
drivers/nvmem/Makefile | 2 +
drivers/nvmem/bcm-ocotp.c | 335 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 349 insertions(+)
create mode 100644 drivers/nvmem/bcm-ocotp.c


I can pick this patch along with dt bindings document, but dts patch has to go via arm-soc tree.

Thanks,
srini



diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index ba140ea..06935a7 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -80,6 +80,18 @@ 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
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 8f942a0..71781ca 100644
--- a/drivers/nvmem/Makefile
+++ b/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
diff --git a/drivers/nvmem/bcm-ocotp.c b/drivers/nvmem/bcm-ocotp.c
new file mode 100644
index 0000000..646cadb
--- /dev/null
+++ b/drivers/nvmem/bcm-ocotp.c
@@ -0,0 +1,335 @@
+/*
+ * 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");