nvmem: lan9662-otp: add support

Add support for OTP controller available on LAN9662. The OTPC controls
the access to a non-volatile memory. The size of the memory is 8KB.
The OTPC can access the memory based on an offset.
Implement both the read and the write functionality.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220916122100.170016-13-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 7f25579..ec8a49c 100644 (file)
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -98,6 +98,14 @@ config NVMEM_JZ4780_EFUSE
          To compile this driver as a module, choose M here: the module
          will be called nvmem_jz4780_efuse.
 
+config NVMEM_LAN9662_OTPC
+       tristate "Microchip LAN9662 OTP controller support"
+       depends on SOC_LAN966 || COMPILE_TEST
+       depends on HAS_IOMEM
+       help
+         This driver enables the OTP controller available on Microchip LAN9662
+         SoCs. It controls the access to the OTP memory connected to it.
+
 config NVMEM_LAYERSCAPE_SFP
        tristate "Layerscape SFP (Security Fuse Processor) support"
        depends on ARCH_LAYERSCAPE || COMPILE_TEST

diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index bac799b..fa80fe1 100644 (file)
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -21,6 +21,8 @@ obj-$(CONFIG_NVMEM_IMX_OCOTP_SCU)     += nvmem-imx-ocotp-scu.o
 nvmem-imx-ocotp-scu-y                  := imx-ocotp-scu.o
 obj-$(CONFIG_NVMEM_JZ4780_EFUSE)       += nvmem_jz4780_efuse.o
 nvmem_jz4780_efuse-y                   := jz4780-efuse.o
+obj-$(CONFIG_NVMEM_LAN9662_OTPC)       += nvmem-lan9662-otpc.o
+nvmem-lan9662-otpc-y           := lan9662-otpc.o
 obj-$(CONFIG_NVMEM_LAYERSCAPE_SFP)     += nvmem-layerscape-sfp.o
 nvmem-layerscape-sfp-y                 := layerscape-sfp.o
 obj-$(CONFIG_NVMEM_LPC18XX_EEPROM)     += nvmem_lpc18xx_eeprom.o

diff --git a/drivers/nvmem/lan9662-otpc.c b/drivers/nvmem/lan9662-otpc.c
new file mode 100644 (file)
index 0000000..f6732fd
--- /dev/null
+++ b/drivers/nvmem/lan9662-otpc.c
@@ -0,0 +1,222 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#define OTP_OTP_PWR_DN(t)                      (t + 0x00)
+#define OTP_OTP_PWR_DN_OTP_PWRDN_N             BIT(0)
+#define OTP_OTP_ADDR_HI(t)                     (t + 0x04)
+#define OTP_OTP_ADDR_LO(t)                     (t + 0x08)
+#define OTP_OTP_PRGM_DATA(t)                   (t + 0x10)
+#define OTP_OTP_PRGM_MODE(t)                   (t + 0x14)
+#define OTP_OTP_PRGM_MODE_OTP_PGM_MODE_BYTE    BIT(0)
+#define OTP_OTP_RD_DATA(t)                     (t + 0x18)
+#define OTP_OTP_FUNC_CMD(t)                    (t + 0x20)
+#define OTP_OTP_FUNC_CMD_OTP_PROGRAM           BIT(1)
+#define OTP_OTP_FUNC_CMD_OTP_READ              BIT(0)
+#define OTP_OTP_CMD_GO(t)                      (t + 0x28)
+#define OTP_OTP_CMD_GO_OTP_GO                  BIT(0)
+#define OTP_OTP_PASS_FAIL(t)                   (t + 0x2c)
+#define OTP_OTP_PASS_FAIL_OTP_READ_PROHIBITED  BIT(3)
+#define OTP_OTP_PASS_FAIL_OTP_WRITE_PROHIBITED BIT(2)
+#define OTP_OTP_PASS_FAIL_OTP_FAIL             BIT(0)
+#define OTP_OTP_STATUS(t)                      (t + 0x30)
+#define OTP_OTP_STATUS_OTP_CPUMPEN             BIT(1)
+#define OTP_OTP_STATUS_OTP_BUSY                        BIT(0)
+
+#define OTP_MEM_SIZE 8192
+#define OTP_SLEEP_US 10
+#define OTP_TIMEOUT_US 500000
+
+struct lan9662_otp {
+       struct device *dev;
+       void __iomem *base;
+};
+
+static bool lan9662_otp_wait_flag_clear(void __iomem *reg, u32 flag)
+{
+       u32 val;
+
+       return readl_poll_timeout(reg, val, !(val & flag),
+                                 OTP_SLEEP_US, OTP_TIMEOUT_US);
+}
+
+static int lan9662_otp_power(struct lan9662_otp *otp, bool up)
+{
+       void __iomem *pwrdn = OTP_OTP_PWR_DN(otp->base);
+
+       if (up) {
+               writel(readl(pwrdn) & ~OTP_OTP_PWR_DN_OTP_PWRDN_N, pwrdn);
+               if (lan9662_otp_wait_flag_clear(OTP_OTP_STATUS(otp->base),
+                                               OTP_OTP_STATUS_OTP_CPUMPEN))
+                       return -ETIMEDOUT;
+       } else {
+               writel(readl(pwrdn) | OTP_OTP_PWR_DN_OTP_PWRDN_N, pwrdn);
+       }
+
+       return 0;
+}
+
+static int lan9662_otp_execute(struct lan9662_otp *otp)
+{
+       if (lan9662_otp_wait_flag_clear(OTP_OTP_CMD_GO(otp->base),
+                                       OTP_OTP_CMD_GO_OTP_GO))
+               return -ETIMEDOUT;
+
+       if (lan9662_otp_wait_flag_clear(OTP_OTP_STATUS(otp->base),
+                                       OTP_OTP_STATUS_OTP_BUSY))
+               return -ETIMEDOUT;
+
+       return 0;
+}
+
+static void lan9662_otp_set_address(struct lan9662_otp *otp, u32 offset)
+{
+       writel(0xff & (offset >> 8), OTP_OTP_ADDR_HI(otp->base));
+       writel(0xff & offset, OTP_OTP_ADDR_LO(otp->base));
+}
+
+static int lan9662_otp_read_byte(struct lan9662_otp *otp, u32 offset, u8 *dst)
+{
+       u32 pass;
+       int rc;
+
+       lan9662_otp_set_address(otp, offset);
+       writel(OTP_OTP_FUNC_CMD_OTP_READ, OTP_OTP_FUNC_CMD(otp->base));
+       writel(OTP_OTP_CMD_GO_OTP_GO, OTP_OTP_CMD_GO(otp->base));
+       rc = lan9662_otp_execute(otp);
+       if (!rc) {
+               pass = readl(OTP_OTP_PASS_FAIL(otp->base));
+               if (pass & OTP_OTP_PASS_FAIL_OTP_READ_PROHIBITED)
+                       return -EACCES;
+               *dst = (u8) readl(OTP_OTP_RD_DATA(otp->base));
+       }
+       return rc;
+}
+
+static int lan9662_otp_write_byte(struct lan9662_otp *otp, u32 offset, u8 data)
+{
+       u32 pass;
+       int rc;
+
+       lan9662_otp_set_address(otp, offset);
+       writel(OTP_OTP_PRGM_MODE_OTP_PGM_MODE_BYTE, OTP_OTP_PRGM_MODE(otp->base));
+       writel(data, OTP_OTP_PRGM_DATA(otp->base));
+       writel(OTP_OTP_FUNC_CMD_OTP_PROGRAM, OTP_OTP_FUNC_CMD(otp->base));
+       writel(OTP_OTP_CMD_GO_OTP_GO, OTP_OTP_CMD_GO(otp->base));
+
+       rc = lan9662_otp_execute(otp);
+       if (!rc) {
+               pass = readl(OTP_OTP_PASS_FAIL(otp->base));
+               if (pass & OTP_OTP_PASS_FAIL_OTP_WRITE_PROHIBITED)
+                       return -EACCES;
+               if (pass & OTP_OTP_PASS_FAIL_OTP_FAIL)
+                       return -EIO;
+       }
+       return rc;
+}
+
+static int lan9662_otp_read(void *context, unsigned int offset,
+                           void *_val, size_t bytes)
+{
+       struct lan9662_otp *otp = context;
+       u8 *val = _val;
+       uint8_t data;
+       int i, rc = 0;
+
+       lan9662_otp_power(otp, true);
+       for (i = 0; i < bytes; i++) {
+               rc = lan9662_otp_read_byte(otp, offset + i, &data);
+               if (rc < 0)
+                       break;
+               *val++ = data;
+       }
+       lan9662_otp_power(otp, false);
+
+       return rc;
+}
+
+static int lan9662_otp_write(void *context, unsigned int offset,
+                            void *_val, size_t bytes)
+{
+       struct lan9662_otp *otp = context;
+       u8 *val = _val;
+       u8 data, newdata;
+       int i, rc = 0;
+
+       lan9662_otp_power(otp, true);
+       for (i = 0; i < bytes; i++) {
+               /* Skip zero bytes */
+               if (val[i]) {
+                       rc = lan9662_otp_read_byte(otp, offset + i, &data);
+                       if (rc < 0)
+                               break;
+
+                       newdata = data | val[i];
+                       if (newdata == data)
+                               continue;
+
+                       rc = lan9662_otp_write_byte(otp, offset + i,
+                                                     newdata);
+                       if (rc < 0)
+                               break;
+               }
+       }
+       lan9662_otp_power(otp, false);
+
+       return rc;
+}
+
+static struct nvmem_config otp_config = {
+       .name = "lan9662-otp",
+       .stride = 1,
+       .word_size = 1,
+       .reg_read = lan9662_otp_read,
+       .reg_write = lan9662_otp_write,
+       .size = OTP_MEM_SIZE,
+};
+
+static int lan9662_otp_probe(struct platform_device *pdev)
+{
+       struct device *dev = &pdev->dev;
+       struct nvmem_device *nvmem;
+       struct lan9662_otp *otp;
+
+       otp = devm_kzalloc(&pdev->dev, sizeof(*otp), GFP_KERNEL);
+       if (!otp)
+               return -ENOMEM;
+
+       otp->dev = dev;
+       otp->base = devm_platform_ioremap_resource(pdev, 0);
+       if (IS_ERR(otp->base))
+               return PTR_ERR(otp->base);
+
+       otp_config.priv = otp;
+       otp_config.dev = dev;
+
+       nvmem = devm_nvmem_register(dev, &otp_config);
+
+       return PTR_ERR_OR_ZERO(nvmem);
+}
+
+static const struct of_device_id lan9662_otp_match[] = {
+       { .compatible = "microchip,lan9662-otp", },
+       { },
+};
+MODULE_DEVICE_TABLE(of, lan9662_otp_match);
+
+static struct platform_driver lan9662_otp_driver = {
+       .probe = lan9662_otp_probe,
+       .driver = {
+               .name = "lan9662-otp",
+               .of_match_table = lan9662_otp_match,
+       },
+};
+module_platform_driver(lan9662_otp_driver);
+
+MODULE_AUTHOR("Horatiu Vultur <horatiu.vultur@microchip.com>");
+MODULE_DESCRIPTION("lan9662 OTP driver");
+MODULE_LICENSE("GPL");