diff options
Diffstat (limited to 'drivers/nvmem/lpc18xx_eeprom.c')
| -rw-r--r-- | drivers/nvmem/lpc18xx_eeprom.c | 330 |
1 files changed, 330 insertions, 0 deletions
diff --git a/drivers/nvmem/lpc18xx_eeprom.c b/drivers/nvmem/lpc18xx_eeprom.c new file mode 100644 index 000000000..878fce789 --- /dev/null +++ b/drivers/nvmem/lpc18xx_eeprom.c @@ -0,0 +1,330 @@ +/* + * NXP LPC18xx/LPC43xx EEPROM memory NVMEM driver + * + * Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + */ + +#include <linux/clk.h> +#include <linux/device.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/nvmem-provider.h> +#include <linux/platform_device.h> +#include <linux/regmap.h> +#include <linux/reset.h> + +/* Registers */ +#define LPC18XX_EEPROM_AUTOPROG 0x00c +#define LPC18XX_EEPROM_AUTOPROG_WORD 0x1 + +#define LPC18XX_EEPROM_CLKDIV 0x014 + +#define LPC18XX_EEPROM_PWRDWN 0x018 +#define LPC18XX_EEPROM_PWRDWN_NO 0x0 +#define LPC18XX_EEPROM_PWRDWN_YES 0x1 + +#define LPC18XX_EEPROM_INTSTAT 0xfe0 +#define LPC18XX_EEPROM_INTSTAT_END_OF_PROG BIT(2) + +#define LPC18XX_EEPROM_INTSTATCLR 0xfe8 +#define LPC18XX_EEPROM_INTSTATCLR_PROG_CLR_ST BIT(2) + +/* Fixed page size (bytes) */ +#define LPC18XX_EEPROM_PAGE_SIZE 0x80 + +/* EEPROM device requires a ~1500 kHz clock (min 800 kHz, max 1600 kHz) */ +#define LPC18XX_EEPROM_CLOCK_HZ 1500000 + +/* EEPROM requires 3 ms of erase/program time between each writing */ +#define LPC18XX_EEPROM_PROGRAM_TIME 3 + +struct lpc18xx_eeprom_dev { + struct clk *clk; + void __iomem *reg_base; + void __iomem *mem_base; + struct nvmem_device *nvmem; + unsigned reg_bytes; + unsigned val_bytes; +}; + +static struct regmap_config lpc18xx_regmap_config = { + .reg_bits = 32, + .reg_stride = 4, + .val_bits = 32, +}; + +static inline void lpc18xx_eeprom_writel(struct lpc18xx_eeprom_dev *eeprom, + u32 reg, u32 val) +{ + writel(val, eeprom->reg_base + reg); +} + +static inline u32 lpc18xx_eeprom_readl(struct lpc18xx_eeprom_dev *eeprom, + u32 reg) +{ + return readl(eeprom->reg_base + reg); +} + +static int lpc18xx_eeprom_busywait_until_prog(struct lpc18xx_eeprom_dev *eeprom) +{ + unsigned long end; + u32 val; + + /* Wait until EEPROM program operation has finished */ + end = jiffies + msecs_to_jiffies(LPC18XX_EEPROM_PROGRAM_TIME * 10); + + while (time_is_after_jiffies(end)) { + val = lpc18xx_eeprom_readl(eeprom, LPC18XX_EEPROM_INTSTAT); + + if (val & LPC18XX_EEPROM_INTSTAT_END_OF_PROG) { + lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_INTSTATCLR, + LPC18XX_EEPROM_INTSTATCLR_PROG_CLR_ST); + return 0; + } + + usleep_range(LPC18XX_EEPROM_PROGRAM_TIME * USEC_PER_MSEC, + (LPC18XX_EEPROM_PROGRAM_TIME + 1) * USEC_PER_MSEC); + } + + return -ETIMEDOUT; +} + +static int lpc18xx_eeprom_gather_write(void *context, const void *reg, + size_t reg_size, const void *val, + size_t val_size) +{ + struct lpc18xx_eeprom_dev *eeprom = context; + unsigned int offset = *(u32 *)reg; + int ret; + + if (offset % lpc18xx_regmap_config.reg_stride) + return -EINVAL; + + lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN, + LPC18XX_EEPROM_PWRDWN_NO); + + /* Wait 100 us while the EEPROM wakes up */ + usleep_range(100, 200); + + while (val_size) { + writel(*(u32 *)val, eeprom->mem_base + offset); + ret = lpc18xx_eeprom_busywait_until_prog(eeprom); + if (ret < 0) + return ret; + + val_size -= eeprom->val_bytes; + val += eeprom->val_bytes; + offset += eeprom->val_bytes; + } + + lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN, + LPC18XX_EEPROM_PWRDWN_YES); + + return 0; +} + +static int lpc18xx_eeprom_write(void *context, const void *data, size_t count) +{ + struct lpc18xx_eeprom_dev *eeprom = context; + unsigned int offset = eeprom->reg_bytes; + + if (count <= offset) + return -EINVAL; + + return lpc18xx_eeprom_gather_write(context, data, eeprom->reg_bytes, + data + offset, count - offset); +} + +static int lpc18xx_eeprom_read(void *context, const void *reg, size_t reg_size, + void *val, size_t val_size) +{ + struct lpc18xx_eeprom_dev *eeprom = context; + unsigned int offset = *(u32 *)reg; + + lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN, + LPC18XX_EEPROM_PWRDWN_NO); + + /* Wait 100 us while the EEPROM wakes up */ + usleep_range(100, 200); + + while (val_size) { + *(u32 *)val = readl(eeprom->mem_base + offset); + val_size -= eeprom->val_bytes; + val += eeprom->val_bytes; + offset += eeprom->val_bytes; + } + + lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN, + LPC18XX_EEPROM_PWRDWN_YES); + + return 0; +} + +static struct regmap_bus lpc18xx_eeprom_bus = { + .write = lpc18xx_eeprom_write, + .gather_write = lpc18xx_eeprom_gather_write, + .read = lpc18xx_eeprom_read, + .reg_format_endian_default = REGMAP_ENDIAN_NATIVE, + .val_format_endian_default = REGMAP_ENDIAN_NATIVE, +}; + +static bool lpc18xx_eeprom_writeable_reg(struct device *dev, unsigned int reg) +{ + /* + * The last page contains the EEPROM initialization data and is not + * writable. + */ + return reg <= lpc18xx_regmap_config.max_register - + LPC18XX_EEPROM_PAGE_SIZE; +} + +static bool lpc18xx_eeprom_readable_reg(struct device *dev, unsigned int reg) +{ + return reg <= lpc18xx_regmap_config.max_register; +} + +static struct nvmem_config lpc18xx_nvmem_config = { + .name = "lpc18xx-eeprom", + .owner = THIS_MODULE, +}; + +static int lpc18xx_eeprom_probe(struct platform_device *pdev) +{ + struct lpc18xx_eeprom_dev *eeprom; + struct device *dev = &pdev->dev; + struct reset_control *rst; + unsigned long clk_rate; + struct regmap *regmap; + struct resource *res; + int ret; + + eeprom = devm_kzalloc(dev, sizeof(*eeprom), GFP_KERNEL); + if (!eeprom) + return -ENOMEM; + + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "reg"); + eeprom->reg_base = devm_ioremap_resource(dev, res); + if (IS_ERR(eeprom->reg_base)) + return PTR_ERR(eeprom->reg_base); + + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mem"); + eeprom->mem_base = devm_ioremap_resource(dev, res); + if (IS_ERR(eeprom->mem_base)) + return PTR_ERR(eeprom->mem_base); + + eeprom->clk = devm_clk_get(&pdev->dev, "eeprom"); + if (IS_ERR(eeprom->clk)) { + dev_err(&pdev->dev, "failed to get eeprom clock\n"); + return PTR_ERR(eeprom->clk); + } + + ret = clk_prepare_enable(eeprom->clk); + if (ret < 0) { + dev_err(dev, "failed to prepare/enable eeprom clk: %d\n", ret); + return ret; + } + + rst = devm_reset_control_get(dev, NULL); + if (IS_ERR(rst)) { + dev_err(dev, "failed to get reset: %ld\n", PTR_ERR(rst)); + ret = PTR_ERR(rst); + goto err_clk; + } + + ret = reset_control_assert(rst); + if (ret < 0) { + dev_err(dev, "failed to assert reset: %d\n", ret); + goto err_clk; + } + + eeprom->val_bytes = lpc18xx_regmap_config.val_bits / BITS_PER_BYTE; + eeprom->reg_bytes = lpc18xx_regmap_config.reg_bits / BITS_PER_BYTE; + + /* + * Clock rate is generated by dividing the system bus clock by the + * division factor, contained in the divider register (minus 1 encoded). + */ + clk_rate = clk_get_rate(eeprom->clk); + clk_rate = DIV_ROUND_UP(clk_rate, LPC18XX_EEPROM_CLOCK_HZ) - 1; + lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_CLKDIV, clk_rate); + + /* + * Writing a single word to the page will start the erase/program cycle + * automatically + */ + lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_AUTOPROG, + LPC18XX_EEPROM_AUTOPROG_WORD); + + lpc18xx_eeprom_writel(eeprom, LPC18XX_EEPROM_PWRDWN, + LPC18XX_EEPROM_PWRDWN_YES); + + lpc18xx_regmap_config.max_register = resource_size(res) - 1; + lpc18xx_regmap_config.writeable_reg = lpc18xx_eeprom_writeable_reg; + lpc18xx_regmap_config.readable_reg = lpc18xx_eeprom_readable_reg; + + regmap = devm_regmap_init(dev, &lpc18xx_eeprom_bus, eeprom, + &lpc18xx_regmap_config); + if (IS_ERR(regmap)) { + dev_err(dev, "regmap init failed: %ld\n", PTR_ERR(regmap)); + ret = PTR_ERR(regmap); + goto err_clk; + } + + lpc18xx_nvmem_config.dev = dev; + + eeprom->nvmem = nvmem_register(&lpc18xx_nvmem_config); + if (IS_ERR(eeprom->nvmem)) { + ret = PTR_ERR(eeprom->nvmem); + goto err_clk; + } + + platform_set_drvdata(pdev, eeprom); + + return 0; + +err_clk: + clk_disable_unprepare(eeprom->clk); + + return ret; +} + +static int lpc18xx_eeprom_remove(struct platform_device *pdev) +{ + struct lpc18xx_eeprom_dev *eeprom = platform_get_drvdata(pdev); + int ret; + + ret = nvmem_unregister(eeprom->nvmem); + if (ret < 0) + return ret; + + clk_disable_unprepare(eeprom->clk); + + return 0; +} + +static const struct of_device_id lpc18xx_eeprom_of_match[] = { + { .compatible = "nxp,lpc1857-eeprom" }, + { }, +}; +MODULE_DEVICE_TABLE(of, lpc18xx_eeprom_of_match); + +static struct platform_driver lpc18xx_eeprom_driver = { + .probe = lpc18xx_eeprom_probe, + .remove = lpc18xx_eeprom_remove, + .driver = { + .name = "lpc18xx-eeprom", + .of_match_table = lpc18xx_eeprom_of_match, + }, +}; + +module_platform_driver(lpc18xx_eeprom_driver); + +MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>"); +MODULE_DESCRIPTION("NXP LPC18xx EEPROM memory Driver"); +MODULE_LICENSE("GPL v2"); |