Re: [PATCH v5 1/6] nvmem: add driver for JZ4780 efuse

Hi Nikolaus,

Le sam., févr. 22, 2020 at 11:25, H. Nikolaus Schaller hns@goldelico.com a écrit :

From: PrasannaKumar Muralidharan prasannatsmkumar@gmail.com

This patch brings support for the JZ4780 efuse. Currently it only exposes a read only access to the entire 8K bits efuse memory and nvmem cells.

Tested-by: Mathieu Malaterre malat@debian.org Signed-off-by: PrasannaKumar Muralidharan prasannatsmkumar@gmail.com Signed-off-by: Mathieu Malaterre malat@debian.org Signed-off-by: H. Nikolaus Schaller hns@goldelico.com Signed-off-by: Paul Cercueil paul@crapouillou.net

---

drivers/nvmem/Kconfig | 10 ++ drivers/nvmem/Makefile | 2 + drivers/nvmem/jz4780-efuse.c | 229 +++++++++++++++++++++++++++++++++++ 3 files changed, 241 insertions(+) create mode 100644 drivers/nvmem/jz4780-efuse.c

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig index 35efab1ba8d9..8143e6e1dd82 100644 --- a/drivers/nvmem/Kconfig +++ b/drivers/nvmem/Kconfig @@ -55,6 +55,16 @@ config NVMEM_IMX_OCOTP_SCU This is a driver for the SCU On-Chip OTP Controller (OCOTP) available on i.MX8 SoCs.

+config JZ4780_EFUSE

• tristate "JZ4780 EFUSE Memory Support"
• depends on MACH_INGENIC || COMPILE_TEST
• depends on HAS_IOMEM

You're using regmap, so you need to select REGMAP_MMIO here.

• help

•  Say Y here to include support for JZ4780 efuse memory found on
  

•  all JZ4780 SoC based devices.
  

•  To compile this driver as a module, choose M here: the module
  

•  will be called nvmem_jz4780_efuse.
  

config NVMEM_LPC18XX_EEPROM tristate "NXP LPC18XX EEPROM Memory Support" depends on ARCH_LPC18XX || COMPILE_TEST diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile index 6b466cd1427b..65a268d17807 100644 --- a/drivers/nvmem/Makefile +++ b/drivers/nvmem/Makefile @@ -18,6 +18,8 @@ obj-$(CONFIG_NVMEM_IMX_OCOTP) += nvmem-imx-ocotp.o nvmem-imx-ocotp-y := imx-ocotp.o obj-$(CONFIG_NVMEM_IMX_OCOTP_SCU) += nvmem-imx-ocotp-scu.o nvmem-imx-ocotp-scu-y := imx-ocotp-scu.o +obj-$(CONFIG_JZ4780_EFUSE) += nvmem_jz4780_efuse.o +nvmem_jz4780_efuse-y := jz4780-efuse.o obj-$(CONFIG_NVMEM_LPC18XX_EEPROM) += nvmem_lpc18xx_eeprom.o nvmem_lpc18xx_eeprom-y := lpc18xx_eeprom.o obj-$(CONFIG_NVMEM_LPC18XX_OTP) += nvmem_lpc18xx_otp.o diff --git a/drivers/nvmem/jz4780-efuse.c b/drivers/nvmem/jz4780-efuse.c new file mode 100644 index 000000000000..08b63de0e9cc --- /dev/null +++ b/drivers/nvmem/jz4780-efuse.c @@ -0,0 +1,229 @@ +// 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)

+#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;
• unsigned int rd_adj;
• unsigned int rd_strobe;

+};

+/* We read 32 byte chunks to avoid complexity in the driver. */

I don't see how reading 32 byte chunks avoids complexity in the driver; the 'size' variable here could very well be an argument.

+static int jz4780_efuse_read_32bytes(struct jz4780_efuse *efuse, char *buf,

• 		     unsigned int addr)
  

+{

• unsigned int tmp;
• u32 ctrl;
• int ret;
• const int size = 32;
• ctrl = (addr << EFUCTRL_ADDR_SHIFT)

• | ((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;
  

• }
• return regmap_bulk_read(efuse->map, JZ_EFUDATA(0),

• 		buf, size / sizeof(u32));
  

+}

+/* main entry point */ +static int jz4780_efuse_read(void *context, unsigned int offset,

• 	     void *val, size_t bytes)
  

+{

• struct jz4780_efuse *efuse = context;
• int ret;
• const int size = 32;
• while (bytes > 0) {

• unsigned int start = offset & ~(size - 1);
  

• unsigned int chunk = min(bytes, (start + size) - offset);
  

Why do you need to check for the address alignment?

• if (start == offset && chunk == size) {
  

• 	ret = jz4780_efuse_read_32bytes(efuse, val, start);
  

• 	if (ret < 0)
  

• 		return ret;
  

• } else {
  

• 	char buf[32];
  

• 	ret = jz4780_efuse_read_32bytes(efuse, buf, start);
  

• 	if (ret < 0)
  

• 		return ret;
  

• 	memcpy(val, &buf[offset - start], chunk);
  

Why do you need this cumbersome process of reading 32 bytes if you need less than that? This looks over-complex to me.

• }
  

• val += chunk;
  

• offset += chunk;
  

• bytes -= chunk;
  

• }
• return 0;

+}

+static struct nvmem_config jz4780_efuse_nvmem_config __initdata = {

• .name = "jz4780-efuse",
• .size = 1024,

The efuse is 8 KiB.

• .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 int jz4780_efuse_probe(struct platform_device *pdev) +{

• struct nvmem_device *nvmem;
• struct jz4780_efuse *efuse;
• struct nvmem_config cfg;
• unsigned long clk_rate;
• struct device *dev = &pdev->dev;
• void __iomem *regs;
• 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);
  

• clk_rate = clk_get_rate(efuse->clk);

You didn't enable the clock before, so clk_get_rate can return a bogus value.

• efuse->dev = dev;
• /*

• * rd_adj and rd_strobe are 4 bit values
  

• * bus clk period * (rd_adj + 1) > 6.5ns
  

• * bus clk period * (rd_adj + 5 + rd_strobe) > 35ns
  

• */
  

• efuse->rd_adj = (((6500 * (clk_rate / 1000000)) / 1000000) + 1) - 1;

I can't get my head around this calculus. Try this:

/* 1 / 6.5ns == 153846154 Hz */ efuse->rd_adj = clk_rate / 153846154;

The efuse read should be *at least* 6.5ns, so no need to bother with the -1/+1.

• efuse->rd_strobe = ((((35000 * (clk_rate / 1000000)) / 1000000) + 1)

• 				- 5 - efuse->rd_adj);
  

/* 1 / 35ns == 28571429 Hz */ efuse->rd_strobe = max(0, clk_rate / 28571429 + 1 - 5 - efuse->rd_adj);

• if (efuse->rd_adj > 0x1F || efuse->rd_strobe > 0x1F) {

• 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),
  

• 	   (efuse->rd_adj << EFUCFG_RD_ADJ_SHIFT) |
  

• 	   (efuse->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);
  

• platform_set_drvdata(pdev, nvmem);

This isn't used anywhere.

• 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");

2.23.0