--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * JZ4780 EFUSE Memory Support driver
+ *
+ * Copyright (c) 2017 PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
+ * Copyright (c) 2020 H. Nikolaus Schaller <hns@goldelico.com>
+ */
+
+/*
+ * Currently supports JZ4780 efuse which has 8K programmable bit.
+ * Efuse is separated into seven segments as below:
+ *
+ * -----------------------------------------------------------------------
+ * | 64 bit | 128 bit | 128 bit | 3520 bit | 8 bit | 2296 bit | 2048 bit |
+ * -----------------------------------------------------------------------
+ *
+ * The rom itself is accessed using a 9 bit address line and an 8 word wide bus
+ * which reads/writes based on strobes. The strobe is configured in the config
+ * register and is based on number of cycles of the bus clock.
+ *
+ * Driver supports read only as the writes are done in the Factory.
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/timer.h>
+
+#define JZ_EFUCTRL (0x0) /* Control Register */
+#define JZ_EFUCFG (0x4) /* Configure Register*/
+#define JZ_EFUSTATE (0x8) /* Status Register */
+#define JZ_EFUDATA(n) (0xC + (n) * 4)
+
+/* We read 32 byte chunks to avoid complexity in the driver. */
+#define JZ_EFU_READ_SIZE 32
+
+#define EFUCTRL_ADDR_MASK 0x3FF
+#define EFUCTRL_ADDR_SHIFT 21
+#define EFUCTRL_LEN_MASK 0x1F
+#define EFUCTRL_LEN_SHIFT 16
+#define EFUCTRL_PG_EN BIT(15)
+#define EFUCTRL_WR_EN BIT(1)
+#define EFUCTRL_RD_EN BIT(0)
+
+#define EFUCFG_INT_EN BIT(31)
+#define EFUCFG_RD_ADJ_MASK 0xF
+#define EFUCFG_RD_ADJ_SHIFT 20
+#define EFUCFG_RD_STR_MASK 0xF
+#define EFUCFG_RD_STR_SHIFT 16
+#define EFUCFG_WR_ADJ_MASK 0xF
+#define EFUCFG_WR_ADJ_SHIFT 12
+#define EFUCFG_WR_STR_MASK 0xFFF
+#define EFUCFG_WR_STR_SHIFT 0
+
+#define EFUSTATE_WR_DONE BIT(1)
+#define EFUSTATE_RD_DONE BIT(0)
+
+struct jz4780_efuse {
+ struct device *dev;
+ struct regmap *map;
+ struct clk *clk;
+};
+
+/* main entry point */
+static int jz4780_efuse_read(void *context, unsigned int offset,
+ void *val, size_t bytes)
+{
+ struct jz4780_efuse *efuse = context;
+
+ while (bytes > 0) {
+ unsigned int start = offset & ~(JZ_EFU_READ_SIZE - 1);
+ unsigned int chunk = min(bytes, (start + JZ_EFU_READ_SIZE)
+ - offset);
+ char buf[JZ_EFU_READ_SIZE];
+ unsigned int tmp;
+ u32 ctrl;
+ int ret;
+
+ ctrl = (start << EFUCTRL_ADDR_SHIFT)
+ | ((JZ_EFU_READ_SIZE - 1) << EFUCTRL_LEN_SHIFT)
+ | EFUCTRL_RD_EN;
+
+ regmap_update_bits(efuse->map, JZ_EFUCTRL,
+ (EFUCTRL_ADDR_MASK << EFUCTRL_ADDR_SHIFT) |
+ (EFUCTRL_LEN_MASK << EFUCTRL_LEN_SHIFT) |
+ EFUCTRL_PG_EN | EFUCTRL_WR_EN |
+ EFUCTRL_RD_EN,
+ ctrl);
+
+ ret = regmap_read_poll_timeout(efuse->map, JZ_EFUSTATE,
+ tmp, tmp & EFUSTATE_RD_DONE,
+ 1 * MSEC_PER_SEC,
+ 50 * MSEC_PER_SEC);
+ if (ret < 0) {
+ dev_err(efuse->dev, "Time out while reading efuse data");
+ return ret;
+ }
+
+ ret = regmap_bulk_read(efuse->map, JZ_EFUDATA(0),
+ buf, JZ_EFU_READ_SIZE / sizeof(u32));
+ if (ret < 0)
+ return ret;
+
+ memcpy(val, &buf[offset - start], chunk);
+
+ val += chunk;
+ offset += chunk;
+ bytes -= chunk;
+ }
+
+ return 0;
+}
+
+static struct nvmem_config jz4780_efuse_nvmem_config = {
+ .name = "jz4780-efuse",
+ .size = 1024,
+ .word_size = 1,
+ .stride = 1,
+ .owner = THIS_MODULE,
+ .reg_read = jz4780_efuse_read,
+};
+
+static const struct regmap_config jz4780_efuse_regmap_config = {
+ .reg_bits = 32,
+ .val_bits = 32,
+ .reg_stride = 4,
+ .max_register = JZ_EFUDATA(7),
+};
+
+static void clk_disable_unprepare_helper(void *clock)
+{
+ clk_disable_unprepare(clock);
+}
+
+static int jz4780_efuse_probe(struct platform_device *pdev)
+{
+ struct nvmem_device *nvmem;
+ struct jz4780_efuse *efuse;
+ struct nvmem_config cfg;
+ unsigned long clk_rate;
+ unsigned long rd_adj;
+ unsigned long rd_strobe;
+ struct device *dev = &pdev->dev;
+ void __iomem *regs;
+ int ret;
+
+ efuse = devm_kzalloc(dev, sizeof(*efuse), GFP_KERNEL);
+ if (!efuse)
+ return -ENOMEM;
+
+ regs = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(regs))
+ return PTR_ERR(regs);
+
+ efuse->map = devm_regmap_init_mmio(dev, regs,
+ &jz4780_efuse_regmap_config);
+ if (IS_ERR(efuse->map))
+ return PTR_ERR(efuse->map);
+
+ efuse->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(efuse->clk))
+ return PTR_ERR(efuse->clk);
+
+ ret = clk_prepare_enable(efuse->clk);
+ if (ret < 0)
+ return ret;
+
+ ret = devm_add_action_or_reset(&pdev->dev,
+ clk_disable_unprepare_helper,
+ efuse->clk);
+ if (ret < 0)
+ return ret;
+
+ clk_rate = clk_get_rate(efuse->clk);
+
+ efuse->dev = dev;
+
+ /*
+ * rd_adj and rd_strobe are 4 bit values
+ * conditions:
+ * bus clk_period * (rd_adj + 1) > 6.5ns
+ * bus clk_period * (rd_adj + 5 + rd_strobe) > 35ns
+ * i.e. rd_adj >= 6.5ns / clk_period
+ * i.e. rd_strobe >= 35 ns / clk_period - 5 - rd_adj + 1
+ * constants:
+ * 1 / 6.5ns == 153846154 Hz
+ * 1 / 35ns == 28571429 Hz
+ */
+
+ rd_adj = clk_rate / 153846154;
+ rd_strobe = clk_rate / 28571429 - 5 - rd_adj + 1;
+
+ if (rd_adj > EFUCFG_RD_ADJ_MASK ||
+ rd_strobe > EFUCFG_RD_STR_MASK) {
+ dev_err(&pdev->dev, "Cannot set clock configuration\n");
+ return -EINVAL;
+ }
+
+ regmap_update_bits(efuse->map, JZ_EFUCFG,
+ (EFUCFG_RD_ADJ_MASK << EFUCFG_RD_ADJ_SHIFT) |
+ (EFUCFG_RD_STR_MASK << EFUCFG_RD_STR_SHIFT),
+ (rd_adj << EFUCFG_RD_ADJ_SHIFT) |
+ (rd_strobe << EFUCFG_RD_STR_SHIFT));
+
+ cfg = jz4780_efuse_nvmem_config;
+ cfg.dev = &pdev->dev;
+ cfg.priv = efuse;
+
+ nvmem = devm_nvmem_register(dev, &cfg);
+ if (IS_ERR(nvmem))
+ return PTR_ERR(nvmem);
+
+ return 0;
+}
+
+static const struct of_device_id jz4780_efuse_match[] = {
+ { .compatible = "ingenic,jz4780-efuse" },
+ { /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, jz4780_efuse_match);
+
+static struct platform_driver jz4780_efuse_driver = {
+ .probe = jz4780_efuse_probe,
+ .driver = {
+ .name = "jz4780-efuse",
+ .of_match_table = jz4780_efuse_match,
+ },
+};
+module_platform_driver(jz4780_efuse_driver);
+
+MODULE_AUTHOR("PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>");
+MODULE_AUTHOR("H. Nikolaus Schaller <hns@goldelico.com>");
+MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
+MODULE_DESCRIPTION("Ingenic JZ4780 efuse driver");
+MODULE_LICENSE("GPL v2");
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