1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * NXP LPC18xx/43xx OTP memory NVMEM driver 4 * 5 * Copyright (c) 2016 Joachim Eastwood <manabian@gmail.com> 6 * 7 * Based on the imx ocotp driver, 8 * Copyright (c) 2015 Pengutronix, Philipp Zabel <p.zabel@pengutronix.de> 9 * 10 * TODO: add support for writing OTP register via API in boot ROM. 11 */ 12 13 #include <linux/io.h> 14 #include <linux/module.h> 15 #include <linux/nvmem-provider.h> 16 #include <linux/of.h> 17 #include <linux/of_device.h> 18 #include <linux/platform_device.h> 19 #include <linux/slab.h> 20 21 /* 22 * LPC18xx OTP memory contains 4 banks with 4 32-bit words. Bank 0 starts 23 * at offset 0 from the base. 24 * 25 * Bank 0 contains the part ID for Flashless devices and is reseverd for 26 * devices with Flash. 27 * Bank 1/2 is generale purpose or AES key storage for secure devices. 28 * Bank 3 contains control data, USB ID and generale purpose words. 29 */ 30 #define LPC18XX_OTP_NUM_BANKS 4 31 #define LPC18XX_OTP_WORDS_PER_BANK 4 32 #define LPC18XX_OTP_WORD_SIZE sizeof(u32) 33 #define LPC18XX_OTP_SIZE (LPC18XX_OTP_NUM_BANKS * \ 34 LPC18XX_OTP_WORDS_PER_BANK * \ 35 LPC18XX_OTP_WORD_SIZE) 36 37 struct lpc18xx_otp { 38 void __iomem *base; 39 }; 40 41 static int lpc18xx_otp_read(void *context, unsigned int offset, 42 void *val, size_t bytes) 43 { 44 struct lpc18xx_otp *otp = context; 45 unsigned int count = bytes >> 2; 46 u32 index = offset >> 2; 47 u32 *buf = val; 48 int i; 49 50 if (count > (LPC18XX_OTP_SIZE - index)) 51 count = LPC18XX_OTP_SIZE - index; 52 53 for (i = index; i < (index + count); i++) 54 *buf++ = readl(otp->base + i * LPC18XX_OTP_WORD_SIZE); 55 56 return 0; 57 } 58 59 static struct nvmem_config lpc18xx_otp_nvmem_config = { 60 .name = "lpc18xx-otp", 61 .read_only = true, 62 .word_size = LPC18XX_OTP_WORD_SIZE, 63 .stride = LPC18XX_OTP_WORD_SIZE, 64 .reg_read = lpc18xx_otp_read, 65 }; 66 67 static int lpc18xx_otp_probe(struct platform_device *pdev) 68 { 69 struct nvmem_device *nvmem; 70 struct lpc18xx_otp *otp; 71 72 otp = devm_kzalloc(&pdev->dev, sizeof(*otp), GFP_KERNEL); 73 if (!otp) 74 return -ENOMEM; 75 76 otp->base = devm_platform_ioremap_resource(pdev, 0); 77 if (IS_ERR(otp->base)) 78 return PTR_ERR(otp->base); 79 80 lpc18xx_otp_nvmem_config.size = LPC18XX_OTP_SIZE; 81 lpc18xx_otp_nvmem_config.dev = &pdev->dev; 82 lpc18xx_otp_nvmem_config.priv = otp; 83 84 nvmem = devm_nvmem_register(&pdev->dev, &lpc18xx_otp_nvmem_config); 85 86 return PTR_ERR_OR_ZERO(nvmem); 87 } 88 89 static const struct of_device_id lpc18xx_otp_dt_ids[] = { 90 { .compatible = "nxp,lpc1850-otp" }, 91 { }, 92 }; 93 MODULE_DEVICE_TABLE(of, lpc18xx_otp_dt_ids); 94 95 static struct platform_driver lpc18xx_otp_driver = { 96 .probe = lpc18xx_otp_probe, 97 .driver = { 98 .name = "lpc18xx_otp", 99 .of_match_table = lpc18xx_otp_dt_ids, 100 }, 101 }; 102 module_platform_driver(lpc18xx_otp_driver); 103 104 MODULE_AUTHOR("Joachim Eastwoood <manabian@gmail.com>"); 105 MODULE_DESCRIPTION("NXP LPC18xx OTP NVMEM driver"); 106 MODULE_LICENSE("GPL v2"); 107