This patch brings read-only support for the Raspberry Pi Customer OTP,
which consists of 8 cells a 32 bits. The driver accesses the OTP via
the mailbox property interface provided by the VPU firmware.
Signed-off-by: Stefan Wahren <stefan.wahren@xxxxxxxx>
Reviewed-by: Eric Anholt <eric@xxxxxxxxxx>
---
drivers/nvmem/Kconfig | 10 ++++
drivers/nvmem/Makefile | 2 +
drivers/nvmem/raspberrypi-otp.c | 113 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 125 insertions(+)
create mode 100644 drivers/nvmem/raspberrypi-otp.c
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 0a7a470e..12106fe 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -192,4 +192,14 @@ config SC27XX_EFUSE
This driver can also be built as a module. If so, the module
will be called nvmem-sc27xx-efuse.
+config NVMEM_RASPBERRYPI_OTP
+ tristate "Raspberry Pi Customer OTP support"
+ depends on (ARCH_BCM2835 && RASPBERRYPI_FIRMWARE) || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE)
+ help
+ This is a driver for access to the Customer OTP block
+ (8 cells * 32 bits) on the Raspberry Pi.
+
+ This driver can also be built as a module. If so, the module
+ will be called nvmem-raspberrypi-otp.
+
endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 4e8c616..dd043bd 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -41,3 +41,5 @@ obj-$(CONFIG_RAVE_SP_EEPROM) += nvmem-rave-sp-eeprom.o
nvmem-rave-sp-eeprom-y := rave-sp-eeprom.o
obj-$(CONFIG_SC27XX_EFUSE) += nvmem-sc27xx-efuse.o
nvmem-sc27xx-efuse-y := sc27xx-efuse.o
+obj-$(CONFIG_NVMEM_RASPBERRYPI_OTP) += nvmem-raspberrypi-otp.o
+nvmem-raspberrypi-otp-y := raspberrypi-otp.o
diff --git a/drivers/nvmem/raspberrypi-otp.c b/drivers/nvmem/raspberrypi-otp.c
new file mode 100644
index 0000000..af6b228
--- /dev/null
+++ b/drivers/nvmem/raspberrypi-otp.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Raspberry Pi Customer OTP driver
+ *
+ * Copyright (C) 2018 Stefan Wahren <stefan.wahren@xxxxxxxx>
+ */
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+#define CUSTOMER_CELLS 8
+
+struct rpi_otp {
+ struct nvmem_device *nvmem;
+ struct rpi_firmware *fw;
+};
+
+/*
+ * Packet definition used by RPI_FIRMWARE_GET_CUSTOMER_OTP
+ */
+struct rpi_customer_otp_packet {
+ u32 index;
+ u32 length;
+ u8 cells[CUSTOMER_CELLS * 4];
+};
+
+static int rpi_otp_read(void *context, unsigned int offset, void *val,
+ size_t bytes)
+{
+ struct rpi_customer_otp_packet packet;
+ struct rpi_otp *otp = context;
+ int ret;
+
+ packet.index = 0;
+ packet.length = CUSTOMER_CELLS;
+ memset(packet.cells, 0xff, sizeof(packet.cells));
+
+ ret = rpi_firmware_property(otp->fw, RPI_FIRMWARE_GET_CUSTOMER_OTP,
+ &packet, sizeof(packet));
+
+ if (ret)
+ return ret;
+
+ /* Request rejected by firmware */
+ if (packet.index)
+ return -EIO;
+
+ memcpy(val, &packet.cells[offset], bytes);
+
+ return 0;
+}
+
+static struct nvmem_config ocotp_config = {
+ .name = "rpi-customer-otp",
+ .read_only = true,
+ .type = NVMEM_TYPE_OTP,
+ .size = CUSTOMER_CELLS * 4,
+ .stride = 4,
+ .word_size = 4,
+ .reg_read = rpi_otp_read,
+};
+
+static int rpi_otp_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *fw_node;
+ struct rpi_otp *otp;
+
+ otp = devm_kzalloc(dev, sizeof(*otp), GFP_KERNEL);
+ if (!otp)
+ return -ENOMEM;
+
+ fw_node = of_get_parent(dev->of_node);
+ if (!fw_node) {
+ dev_err(dev, "Missing firmware node\n");
+ return -ENOENT;
+ }
+
+ otp->fw = rpi_firmware_get(fw_node);
+ of_node_put(fw_node);
+ if (!otp->fw)
+ return -EPROBE_DEFER;
+
+ ocotp_config.priv = otp;
+ ocotp_config.dev = dev;
+ otp->nvmem = devm_nvmem_register(dev, &ocotp_config);
+
+ return PTR_ERR_OR_ZERO(otp->nvmem);
+}
+
+static const struct of_device_id rpi_otp_of_match[] = {
+ { .compatible = "raspberrypi,bcm2835-customer-otp", },
+ { /* sentinel */},
+};
+MODULE_DEVICE_TABLE(of, rpi_otp_of_match);
+
+static struct platform_driver rpi_otp_driver = {
+ .probe = rpi_otp_probe,
+ .driver = {
+ .name = "rpi-customer-otp",
+ .of_match_table = rpi_otp_of_match,
+ },
+};
+module_platform_driver(rpi_otp_driver);
+
+MODULE_AUTHOR("Stefan Wahren <stefan.wahren@xxxxxxxx>");
+MODULE_DESCRIPTION("Raspberry Pi Customer OTP driver");
+MODULE_LICENSE("GPL");
--
2.7.4
