diff options
Diffstat (limited to 'drivers/nvmem/microchip-otpc.c')
-rw-r--r-- | drivers/nvmem/microchip-otpc.c | 288 |
1 files changed, 288 insertions, 0 deletions
diff --git a/drivers/nvmem/microchip-otpc.c b/drivers/nvmem/microchip-otpc.c new file mode 100644 index 000000000000..436e0dc4f337 --- /dev/null +++ b/drivers/nvmem/microchip-otpc.c @@ -0,0 +1,288 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * OTP Memory controller + * + * Copyright (C) 2022 Microchip Technology Inc. and its subsidiaries + * + * Author: Claudiu Beznea <claudiu.beznea@microchip.com> + */ + +#include <linux/bitfield.h> +#include <linux/iopoll.h> +#include <linux/module.h> +#include <linux/nvmem-provider.h> +#include <linux/of.h> +#include <linux/platform_device.h> + +#define MCHP_OTPC_CR (0x0) +#define MCHP_OTPC_CR_READ BIT(6) +#define MCHP_OTPC_MR (0x4) +#define MCHP_OTPC_MR_ADDR GENMASK(31, 16) +#define MCHP_OTPC_AR (0x8) +#define MCHP_OTPC_SR (0xc) +#define MCHP_OTPC_SR_READ BIT(6) +#define MCHP_OTPC_HR (0x20) +#define MCHP_OTPC_HR_SIZE GENMASK(15, 8) +#define MCHP_OTPC_DR (0x24) + +#define MCHP_OTPC_NAME "mchp-otpc" +#define MCHP_OTPC_SIZE (11 * 1024) + +/** + * struct mchp_otpc - OTPC private data structure + * @base: base address + * @dev: struct device pointer + * @packets: list of packets in OTP memory + * @npackets: number of packets in OTP memory + */ +struct mchp_otpc { + void __iomem *base; + struct device *dev; + struct list_head packets; + u32 npackets; +}; + +/** + * struct mchp_otpc_packet - OTPC packet data structure + * @list: list head + * @id: packet ID + * @offset: packet offset (in words) in OTP memory + */ +struct mchp_otpc_packet { + struct list_head list; + u32 id; + u32 offset; +}; + +static struct mchp_otpc_packet *mchp_otpc_id_to_packet(struct mchp_otpc *otpc, + u32 id) +{ + struct mchp_otpc_packet *packet; + + if (id >= otpc->npackets) + return NULL; + + list_for_each_entry(packet, &otpc->packets, list) { + if (packet->id == id) + return packet; + } + + return NULL; +} + +static int mchp_otpc_prepare_read(struct mchp_otpc *otpc, + unsigned int offset) +{ + u32 tmp; + + /* Set address. */ + tmp = readl_relaxed(otpc->base + MCHP_OTPC_MR); + tmp &= ~MCHP_OTPC_MR_ADDR; + tmp |= FIELD_PREP(MCHP_OTPC_MR_ADDR, offset); + writel_relaxed(tmp, otpc->base + MCHP_OTPC_MR); + + /* Set read. */ + tmp = readl_relaxed(otpc->base + MCHP_OTPC_CR); + tmp |= MCHP_OTPC_CR_READ; + writel_relaxed(tmp, otpc->base + MCHP_OTPC_CR); + + /* Wait for packet to be transferred into temporary buffers. */ + return read_poll_timeout(readl_relaxed, tmp, !(tmp & MCHP_OTPC_SR_READ), + 10000, 2000, false, otpc->base + MCHP_OTPC_SR); +} + +/* + * OTPC memory is organized into packets. Each packets contains a header and + * a payload. Header is 4 bytes long and contains the size of the payload. + * Payload size varies. The memory footprint is something as follows: + * + * Memory offset Memory footprint Packet ID + * ------------- ---------------- --------- + * + * 0x0 +------------+ <-- packet 0 + * | header 0 | + * 0x4 +------------+ + * | payload 0 | + * . . + * . ... . + * . . + * offset1 +------------+ <-- packet 1 + * | header 1 | + * offset1 + 0x4 +------------+ + * | payload 1 | + * . . + * . ... . + * . . + * offset2 +------------+ <-- packet 2 + * . . + * . ... . + * . . + * offsetN +------------+ <-- packet N + * | header N | + * offsetN + 0x4 +------------+ + * | payload N | + * . . + * . ... . + * . . + * +------------+ + * + * where offset1, offset2, offsetN depends on the size of payload 0, payload 1, + * payload N-1. + * + * The access to memory is done on a per packet basis: the control registers + * need to be updated with an offset address (within a packet range) and the + * data registers will be update by controller with information contained by + * that packet. E.g. if control registers are updated with any address within + * the range [offset1, offset2) the data registers are updated by controller + * with packet 1. Header data is accessible though MCHP_OTPC_HR register. + * Payload data is accessible though MCHP_OTPC_DR and MCHP_OTPC_AR registers. + * There is no direct mapping b/w the offset requested by software and the + * offset returned by hardware. + * + * For this, the read function will return the first requested bytes in the + * packet. The user will have to be aware of the memory footprint before doing + * the read request. + */ +static int mchp_otpc_read(void *priv, unsigned int off, void *val, + size_t bytes) +{ + struct mchp_otpc *otpc = priv; + struct mchp_otpc_packet *packet; + u32 *buf = val; + u32 offset; + size_t len = 0; + int ret, payload_size; + + /* + * We reach this point with off being multiple of stride = 4 to + * be able to cross the subsystem. Inside the driver we use continuous + * unsigned integer numbers for packet id, thus devide off by 4 + * before passing it to mchp_otpc_id_to_packet(). + */ + packet = mchp_otpc_id_to_packet(otpc, off / 4); + if (!packet) + return -EINVAL; + offset = packet->offset; + + while (len < bytes) { + ret = mchp_otpc_prepare_read(otpc, offset); + if (ret) + return ret; + + /* Read and save header content. */ + *buf++ = readl_relaxed(otpc->base + MCHP_OTPC_HR); + len += sizeof(*buf); + offset++; + if (len >= bytes) + break; + + /* Read and save payload content. */ + payload_size = FIELD_GET(MCHP_OTPC_HR_SIZE, *(buf - 1)); + writel_relaxed(0UL, otpc->base + MCHP_OTPC_AR); + do { + *buf++ = readl_relaxed(otpc->base + MCHP_OTPC_DR); + len += sizeof(*buf); + offset++; + payload_size--; + } while (payload_size >= 0 && len < bytes); + } + + return 0; +} + +static int mchp_otpc_init_packets_list(struct mchp_otpc *otpc, u32 *size) +{ + struct mchp_otpc_packet *packet; + u32 word, word_pos = 0, id = 0, npackets = 0, payload_size; + int ret; + + INIT_LIST_HEAD(&otpc->packets); + *size = 0; + + while (*size < MCHP_OTPC_SIZE) { + ret = mchp_otpc_prepare_read(otpc, word_pos); + if (ret) + return ret; + + word = readl_relaxed(otpc->base + MCHP_OTPC_HR); + payload_size = FIELD_GET(MCHP_OTPC_HR_SIZE, word); + if (!payload_size) + break; + + packet = devm_kzalloc(otpc->dev, sizeof(*packet), GFP_KERNEL); + if (!packet) + return -ENOMEM; + + packet->id = id++; + packet->offset = word_pos; + INIT_LIST_HEAD(&packet->list); + list_add_tail(&packet->list, &otpc->packets); + + /* Count size by adding header and paload sizes. */ + *size += 4 * (payload_size + 1); + /* Next word: this packet (header, payload) position + 1. */ + word_pos += payload_size + 2; + + npackets++; + } + + otpc->npackets = npackets; + + return 0; +} + +static struct nvmem_config mchp_nvmem_config = { + .name = MCHP_OTPC_NAME, + .type = NVMEM_TYPE_OTP, + .read_only = true, + .word_size = 4, + .stride = 4, + .reg_read = mchp_otpc_read, +}; + +static int mchp_otpc_probe(struct platform_device *pdev) +{ + struct nvmem_device *nvmem; + struct mchp_otpc *otpc; + u32 size; + int ret; + + otpc = devm_kzalloc(&pdev->dev, sizeof(*otpc), GFP_KERNEL); + if (!otpc) + return -ENOMEM; + + otpc->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(otpc->base)) + return PTR_ERR(otpc->base); + + otpc->dev = &pdev->dev; + ret = mchp_otpc_init_packets_list(otpc, &size); + if (ret) + return ret; + + mchp_nvmem_config.dev = otpc->dev; + mchp_nvmem_config.size = size; + mchp_nvmem_config.priv = otpc; + nvmem = devm_nvmem_register(&pdev->dev, &mchp_nvmem_config); + + return PTR_ERR_OR_ZERO(nvmem); +} + +static const struct of_device_id __maybe_unused mchp_otpc_ids[] = { + { .compatible = "microchip,sama7g5-otpc", }, + { }, +}; +MODULE_DEVICE_TABLE(of, mchp_otpc_ids); + +static struct platform_driver mchp_otpc_driver = { + .probe = mchp_otpc_probe, + .driver = { + .name = MCHP_OTPC_NAME, + .of_match_table = of_match_ptr(mchp_otpc_ids), + }, +}; +module_platform_driver(mchp_otpc_driver); + +MODULE_AUTHOR("Claudiu Beznea <claudiu.beznea@microchip.com>"); +MODULE_DESCRIPTION("Microchip SAMA7G5 OTPC driver"); +MODULE_LICENSE("GPL"); |