1 /* 2 * NXP LPC18xx/43xx OTP memory NVMEM driver 3 * 4 * Copyright (c) 2016 Joachim Eastwood <manabian@gmail.com> 5 * 6 * Based on the imx ocotp driver, 7 * Copyright (c) 2015 Pengutronix, Philipp Zabel <p.zabel@pengutronix.de> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License version 2 11 * as published by the Free Software Foundation. 12 * 13 * TODO: add support for writing OTP register via API in boot ROM. 14 */ 15 16 #include <linux/io.h> 17 #include <linux/module.h> 18 #include <linux/nvmem-provider.h> 19 #include <linux/of.h> 20 #include <linux/of_device.h> 21 #include <linux/platform_device.h> 22 #include <linux/slab.h> 23 24 /* 25 * LPC18xx OTP memory contains 4 banks with 4 32-bit words. Bank 0 starts 26 * at offset 0 from the base. 27 * 28 * Bank 0 contains the part ID for Flashless devices and is reseverd for 29 * devices with Flash. 30 * Bank 1/2 is generale purpose or AES key storage for secure devices. 31 * Bank 3 contains control data, USB ID and generale purpose words. 32 */ 33 #define LPC18XX_OTP_NUM_BANKS 4 34 #define LPC18XX_OTP_WORDS_PER_BANK 4 35 #define LPC18XX_OTP_WORD_SIZE sizeof(u32) 36 #define LPC18XX_OTP_SIZE (LPC18XX_OTP_NUM_BANKS * \ 37 LPC18XX_OTP_WORDS_PER_BANK * \ 38 LPC18XX_OTP_WORD_SIZE) 39 40 struct lpc18xx_otp { 41 void __iomem *base; 42 }; 43 44 static int lpc18xx_otp_read(void *context, unsigned int offset, 45 void *val, size_t bytes) 46 { 47 struct lpc18xx_otp *otp = context; 48 unsigned int count = bytes >> 2; 49 u32 index = offset >> 2; 50 u32 *buf = val; 51 int i; 52 53 if (count > (LPC18XX_OTP_SIZE - index)) 54 count = LPC18XX_OTP_SIZE - index; 55 56 for (i = index; i < (index + count); i++) 57 *buf++ = readl(otp->base + i * LPC18XX_OTP_WORD_SIZE); 58 59 return 0; 60 } 61 62 static struct nvmem_config lpc18xx_otp_nvmem_config = { 63 .name = "lpc18xx-otp", 64 .read_only = true, 65 .word_size = LPC18XX_OTP_WORD_SIZE, 66 .stride = LPC18XX_OTP_WORD_SIZE, 67 .reg_read = lpc18xx_otp_read, 68 }; 69 70 static int lpc18xx_otp_probe(struct platform_device *pdev) 71 { 72 struct nvmem_device *nvmem; 73 struct lpc18xx_otp *otp; 74 struct resource *res; 75 76 otp = devm_kzalloc(&pdev->dev, sizeof(*otp), GFP_KERNEL); 77 if (!otp) 78 return -ENOMEM; 79 80 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 81 otp->base = devm_ioremap_resource(&pdev->dev, res); 82 if (IS_ERR(otp->base)) 83 return PTR_ERR(otp->base); 84 85 lpc18xx_otp_nvmem_config.size = LPC18XX_OTP_SIZE; 86 lpc18xx_otp_nvmem_config.dev = &pdev->dev; 87 lpc18xx_otp_nvmem_config.priv = otp; 88 89 nvmem = devm_nvmem_register(&pdev->dev, &lpc18xx_otp_nvmem_config); 90 91 return PTR_ERR_OR_ZERO(nvmem); 92 } 93 94 static const struct of_device_id lpc18xx_otp_dt_ids[] = { 95 { .compatible = "nxp,lpc1850-otp" }, 96 { }, 97 }; 98 MODULE_DEVICE_TABLE(of, lpc18xx_otp_dt_ids); 99 100 static struct platform_driver lpc18xx_otp_driver = { 101 .probe = lpc18xx_otp_probe, 102 .driver = { 103 .name = "lpc18xx_otp", 104 .of_match_table = lpc18xx_otp_dt_ids, 105 }, 106 }; 107 module_platform_driver(lpc18xx_otp_driver); 108 109 MODULE_AUTHOR("Joachim Eastwoood <manabian@gmail.com>"); 110 MODULE_DESCRIPTION("NXP LPC18xx OTP NVMEM driver"); 111 MODULE_LICENSE("GPL v2"); 112