[RFC v3 0/9] MIPS: CI20: Add efuse driver for Ingenic JZ4780 and attach to DM9000 for stable MAC addresses

[RFC v3 0/9] MIPS: CI20: Add efuse driver for Ingenic JZ4780 and attach to DM9000 for stable MAC addresses

[H. Nikolaus Schaller]

This series is based on and a follow up for

https://lore.kernel.org/patchwork/cover/868157/

("[v2,0/2] Add efuse driver for Ingenic JZ4780 SoC")

Original authors were
PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Mathieu Malaterre <malat@debian.org>

and there are additions / code improvements by
H. Nikolaus Schaller <hns@goldelico.com>
Paul Cercueil <paul@crapouillou.net>

This setup works, if the dm9000 driver is compiled
as a module.

Therefore it is all RFC level. It is also not completely
checkpatched.


H. Nikolaus Schaller (2):
  MIPS: DTS: CI20: make DM9000 Ethernet controller use NVMEM to find the
    default MAC address
  MIPS: CI20 defconfig: DEMO HACK: make DM9000 a module

Mathieu Malaterre (1):
  MIPS: CI20 defconfig: Probe efuse for CI20

Paul Cercueil (1):
  rework to use regmap

PrasannaKumar Muralidharan (5):
  nvmem: add driver for JZ4780 efuse
  Bindings: nvmem: add bindings for JZ4780 efuse
  Documentation: ABI: nvmem: add documentation for JZ4780 efuse ABI
  nvmem: MAINTAINERS: add maintainer for JZ4780 efuse driver
  MIPS: DTS: JZ4780: define node for JZ4780 efuse

 .../ABI/testing/sysfs-driver-jz4780-efuse     |  16 ++
 .../bindings/nvmem/ingenic,jz4780-efuse.txt   |  17 ++
 MAINTAINERS                                   |   5 +
 arch/mips/boot/dts/ingenic/ci20.dts           |   3 +
 arch/mips/boot/dts/ingenic/jz4780.dtsi        |  17 +-
 arch/mips/configs/ci20_defconfig              |   4 +-
 drivers/nvmem/Kconfig                         |  10 +
 drivers/nvmem/Makefile                        |   2 +
 drivers/nvmem/jz4780-efuse.c                  | 238 ++++++++++++++++++
 9 files changed, 310 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-driver-jz4780-efuse
 create mode 100644 Documentation/devicetree/bindings/nvmem/ingenic,jz4780-efuse.txt
 create mode 100644 drivers/nvmem/jz4780-efuse.c

-- 
2.23.0

[RFC v3 1/9] nvmem: add driver for JZ4780 efuse

[H. Nikolaus Schaller]

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 | 249 +++++++++++++++++++++++++++++++++++
 3 files changed, 261 insertions(+)
 create mode 100644 drivers/nvmem/jz4780-efuse.c

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 35efab1ba8d9..10f8e08f5e31 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_JZ4780 || COMPILE_TEST
+	depends on HAS_IOMEM
+	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..ac03e1900ef9
--- /dev/null
+++ b/drivers/nvmem/jz4780-efuse.c
@@ -0,0 +1,249 @@
+// 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 JZ_EFUSE_START_ADDR		0x200
+
+#define JZ_EFUSE_EFUCTRL_CS		BIT(30)
+#define JZ_EFUSE_EFUCTRL_ADDR_MASK	0x1FF
+#define JZ_EFUSE_EFUCTRL_ADDR_SHIFT	21
+#define JZ_EFUSE_EFUCTRL_LEN_MASK	0x1F
+#define JZ_EFUSE_EFUCTRL_LEN_SHIFT	16
+#define JZ_EFUSE_EFUCTRL_PG_EN		BIT(15)
+#define JZ_EFUSE_EFUCTRL_WR_EN		BIT(1)
+#define JZ_EFUSE_EFUCTRL_RD_EN		BIT(0)
+
+#define JZ_EFUSE_EFUCFG_INT_EN		BIT(31)
+#define JZ_EFUSE_EFUCFG_RD_ADJ_MASK	0xF
+#define JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT	20
+#define JZ_EFUSE_EFUCFG_RD_STR_MASK	0xF
+#define JZ_EFUSE_EFUCFG_RD_STR_SHIFT	16
+#define JZ_EFUSE_EFUCFG_WR_ADJ_MASK	0xF
+#define JZ_EFUSE_EFUCFG_WR_ADJ_SHIFT	12
+#define JZ_EFUSE_EFUCFG_WR_STR_MASK	0xFFF
+#define JZ_EFUSE_EFUCFG_WR_STR_SHIFT	0
+
+#define JZ_EFUSE_EFUSTATE_WR_DONE	BIT(1)
+#define JZ_EFUSE_EFUSTATE_RD_DONE	BIT(0)
+
+struct jz4780_efuse {
+	struct device *dev;
+	void __iomem *iomem;
+	struct clk *clk;
+	unsigned int rd_adj;
+	unsigned int rd_strobe;
+};
+
+/* We read 32 byte chunks to avoid complexity in the driver. */
+static int jz4780_efuse_read_32bytes(struct jz4780_efuse *efuse, char *buf,
+		unsigned int addr)
+{
+	unsigned int tmp = 0;
+	int i = 0;
+	int timeout = 1000;
+	int size = 32;
+
+	/* 1. Set config register */
+	tmp = readl(efuse->iomem + JZ_EFUCFG);
+	tmp &= ~((JZ_EFUSE_EFUCFG_RD_ADJ_MASK << JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
+	| (JZ_EFUSE_EFUCFG_RD_STR_MASK << JZ_EFUSE_EFUCFG_RD_STR_SHIFT));
+	tmp |= (efuse->rd_adj << JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
+	| (efuse->rd_strobe << JZ_EFUSE_EFUCFG_RD_STR_SHIFT);
+	writel(tmp, efuse->iomem + JZ_EFUCFG);
+
+	/*
+	 * 2. Set control register to indicate what to read data address,
+	 * read data numbers and read enable.
+	 */
+	tmp = readl(efuse->iomem + JZ_EFUCTRL);
+	tmp &= ~(JZ_EFUSE_EFUCFG_RD_STR_SHIFT
+		| (JZ_EFUSE_EFUCTRL_ADDR_MASK << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
+		| JZ_EFUSE_EFUCTRL_PG_EN | JZ_EFUSE_EFUCTRL_WR_EN
+		| JZ_EFUSE_EFUCTRL_WR_EN);
+
+	/* Need to select CS bit if address accesses upper 4Kbits memory */
+	if (addr >= (JZ_EFUSE_START_ADDR + 512))
+		tmp |= JZ_EFUSE_EFUCTRL_CS;
+
+	tmp |= (addr << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
+		| ((size - 1) << JZ_EFUSE_EFUCTRL_LEN_SHIFT)
+		| JZ_EFUSE_EFUCTRL_RD_EN;
+	writel(tmp, efuse->iomem + JZ_EFUCTRL);
+
+	/*
+	 * 3. Wait status register RD_DONE set to 1 or EFUSE interrupted,
+	 * software can read EFUSE data buffer 0 - 8 registers.
+	 */
+	do {
+		tmp = readl(efuse->iomem + JZ_EFUSTATE);
+		usleep_range(1000, 2000);
+		if (timeout--)
+			break;
+	} while (!(tmp & JZ_EFUSE_EFUSTATE_RD_DONE));
+
+	if (timeout <= 0) {
+		dev_err(efuse->dev, "Timed out while reading\n");
+		return -EAGAIN;
+	}
+
+	for (i = 0; i < (size / 4); i++)
+		*((unsigned int *)(buf + i * 4))
+			 = readl(efuse->iomem + JZ_EFUDATA(i));
+
+	return 0;
+}
+
+/* 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;
+
+	while (bytes > 0) {
+		unsigned int start = offset & ~(32 - 1);
+		unsigned chunk = min(bytes, (start + 32 - offset));
+
+		if (start == offset && chunk == 32) {
+			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);
+		}
+
+		val += chunk;
+		offset += chunk;
+		bytes -= chunk;
+	}
+
+	return 0;
+}
+
+static struct nvmem_config jz4780_efuse_nvmem_config = {
+	.name = "jz4780-efuse",
+	.read_only = true,
+	.size = 1024,
+	.word_size = 1,
+	.stride = 1,
+	.owner = THIS_MODULE,
+	.reg_read = jz4780_efuse_read,
+};
+
+static int jz4780_efuse_probe(struct platform_device *pdev)
+{
+	struct nvmem_device *nvmem;
+	struct jz4780_efuse *efuse;
+	struct resource *res;
+	unsigned long clk_rate;
+	struct device *dev = &pdev->dev;
+
+	efuse = devm_kzalloc(&pdev->dev, sizeof(*efuse), GFP_KERNEL);
+	if (!efuse)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	efuse->iomem = devm_ioremap(&pdev->dev, res->start, resource_size(res));
+	if (IS_ERR(efuse->iomem))
+		return PTR_ERR(efuse->iomem);
+
+	efuse->clk = devm_clk_get(&pdev->dev, "bus_clk");
+	if (IS_ERR(efuse->clk))
+		return PTR_ERR(efuse->clk);
+
+	clk_rate = clk_get_rate(efuse->clk);
+	/*
+	 * 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;
+	efuse->rd_strobe = ((((35000 * (clk_rate / 1000000)) / 1000000) + 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;
+	}
+	efuse->dev = dev;
+
+	jz4780_efuse_nvmem_config.dev = &pdev->dev;
+	jz4780_efuse_nvmem_config.priv = efuse;
+
+	nvmem = nvmem_register(&jz4780_efuse_nvmem_config);
+	if (IS_ERR(nvmem))
+		return PTR_ERR(nvmem);
+
+	platform_set_drvdata(pdev, nvmem);
+
+	return 0;
+}
+
+static int jz4780_efuse_remove(struct platform_device *pdev)
+{
+	struct nvmem_device *nvmem = platform_get_drvdata(pdev);
+
+	nvmem_unregister(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,
+	.remove = jz4780_efuse_remove,
+	.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_DESCRIPTION("Ingenic JZ4780 efuse driver");
+MODULE_LICENSE("GPL v2");
-- 
2.23.0

[RFC v3 2/9] rework to use regmap

[H. Nikolaus Schaller]

From: Paul Cercueil <paul@crapouillou.net>

should/will be squashed into the previous commit ("nvmem: add driver for JZ4780 efuse")
but is kept separately for this RFC to make the modifications more transparent.
---
 drivers/nvmem/jz4780-efuse.c | 179 ++++++++++++++++-------------------
 1 file changed, 84 insertions(+), 95 deletions(-)

diff --git a/drivers/nvmem/jz4780-efuse.c b/drivers/nvmem/jz4780-efuse.c
index ac03e1900ef9..79dc42431bfe 100644
--- a/drivers/nvmem/jz4780-efuse.c
+++ b/drivers/nvmem/jz4780-efuse.c
@@ -30,38 +30,35 @@
 #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 JZ_EFUSE_START_ADDR		0x200
-
-#define JZ_EFUSE_EFUCTRL_CS		BIT(30)
-#define JZ_EFUSE_EFUCTRL_ADDR_MASK	0x1FF
-#define JZ_EFUSE_EFUCTRL_ADDR_SHIFT	21
-#define JZ_EFUSE_EFUCTRL_LEN_MASK	0x1F
-#define JZ_EFUSE_EFUCTRL_LEN_SHIFT	16
-#define JZ_EFUSE_EFUCTRL_PG_EN		BIT(15)
-#define JZ_EFUSE_EFUCTRL_WR_EN		BIT(1)
-#define JZ_EFUSE_EFUCTRL_RD_EN		BIT(0)
-
-#define JZ_EFUSE_EFUCFG_INT_EN		BIT(31)
-#define JZ_EFUSE_EFUCFG_RD_ADJ_MASK	0xF
-#define JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT	20
-#define JZ_EFUSE_EFUCFG_RD_STR_MASK	0xF
-#define JZ_EFUSE_EFUCFG_RD_STR_SHIFT	16
-#define JZ_EFUSE_EFUCFG_WR_ADJ_MASK	0xF
-#define JZ_EFUSE_EFUCFG_WR_ADJ_SHIFT	12
-#define JZ_EFUSE_EFUCFG_WR_STR_MASK	0xFFF
-#define JZ_EFUSE_EFUCFG_WR_STR_SHIFT	0
-
-#define JZ_EFUSE_EFUSTATE_WR_DONE	BIT(1)
-#define JZ_EFUSE_EFUSTATE_RD_DONE	BIT(0)
+#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;
-	void __iomem *iomem;
+	struct regmap *map;
 	struct clk *clk;
 	unsigned int rd_adj;
 	unsigned int rd_strobe;
@@ -71,59 +68,29 @@ struct jz4780_efuse {
 static int jz4780_efuse_read_32bytes(struct jz4780_efuse *efuse, char *buf,
 		unsigned int addr)
 {
-	unsigned int tmp = 0;
-	int i = 0;
-	int timeout = 1000;
-	int size = 32;
-
-	/* 1. Set config register */
-	tmp = readl(efuse->iomem + JZ_EFUCFG);
-	tmp &= ~((JZ_EFUSE_EFUCFG_RD_ADJ_MASK << JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
-	| (JZ_EFUSE_EFUCFG_RD_STR_MASK << JZ_EFUSE_EFUCFG_RD_STR_SHIFT));
-	tmp |= (efuse->rd_adj << JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
-	| (efuse->rd_strobe << JZ_EFUSE_EFUCFG_RD_STR_SHIFT);
-	writel(tmp, efuse->iomem + JZ_EFUCFG);
-
-	/*
-	 * 2. Set control register to indicate what to read data address,
-	 * read data numbers and read enable.
-	 */
-	tmp = readl(efuse->iomem + JZ_EFUCTRL);
-	tmp &= ~(JZ_EFUSE_EFUCFG_RD_STR_SHIFT
-		| (JZ_EFUSE_EFUCTRL_ADDR_MASK << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
-		| JZ_EFUSE_EFUCTRL_PG_EN | JZ_EFUSE_EFUCTRL_WR_EN
-		| JZ_EFUSE_EFUCTRL_WR_EN);
-
-	/* Need to select CS bit if address accesses upper 4Kbits memory */
-	if (addr >= (JZ_EFUSE_START_ADDR + 512))
-		tmp |= JZ_EFUSE_EFUCTRL_CS;
-
-	tmp |= (addr << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
-		| ((size - 1) << JZ_EFUSE_EFUCTRL_LEN_SHIFT)
-		| JZ_EFUSE_EFUCTRL_RD_EN;
-	writel(tmp, efuse->iomem + JZ_EFUCTRL);
-
-	/*
-	 * 3. Wait status register RD_DONE set to 1 or EFUSE interrupted,
-	 * software can read EFUSE data buffer 0 - 8 registers.
-	 */
-	do {
-		tmp = readl(efuse->iomem + JZ_EFUSTATE);
-		usleep_range(1000, 2000);
-		if (timeout--)
-			break;
-	} while (!(tmp & JZ_EFUSE_EFUSTATE_RD_DONE));
-
-	if (timeout <= 0) {
-		dev_err(efuse->dev, "Timed out while reading\n");
-		return -EAGAIN;
+	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;
 	}
 
-	for (i = 0; i < (size / 4); i++)
-		*((unsigned int *)(buf + i * 4))
-			 = readl(efuse->iomem + JZ_EFUDATA(i));
-
-	return 0;
+	return regmap_bulk_read(efuse->map, JZ_EFUDATA(0), buf, size / sizeof(u32));
 }
 
 /* main entry point */
@@ -132,12 +99,13 @@ static int jz4780_efuse_read(void *context, unsigned int offset,
 {
 	struct jz4780_efuse *efuse = context;
 	int ret;
+	const int size = 32;
 
 	while (bytes > 0) {
-		unsigned int start = offset & ~(32 - 1);
-		unsigned chunk = min(bytes, (start + 32 - offset));
+		unsigned int start = offset & ~(size - 1);
+		unsigned chunk = min(bytes, (start + size) - offset);
 
-		if (start == offset && chunk == 32) {
+		if (start == offset && chunk == size) {
 			ret = jz4780_efuse_read_32bytes(efuse, val, start);
 			if (ret < 0)
 				return ret;
@@ -159,7 +127,7 @@ static int jz4780_efuse_read(void *context, unsigned int offset,
 	return 0;
 }
 
-static struct nvmem_config jz4780_efuse_nvmem_config = {
+static __initdata struct nvmem_config jz4780_efuse_nvmem_config = {
 	.name = "jz4780-efuse",
 	.read_only = true,
 	.size = 1024,
@@ -169,28 +137,42 @@ static struct nvmem_config jz4780_efuse_nvmem_config = {
 	.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 resource *res;
+	struct nvmem_config cfg;
 	unsigned long clk_rate;
 	struct device *dev = &pdev->dev;
+	void __iomem *regs;
 
-	efuse = devm_kzalloc(&pdev->dev, sizeof(*efuse), GFP_KERNEL);
+	efuse = devm_kzalloc(dev, sizeof(*efuse), GFP_KERNEL);
 	if (!efuse)
 		return -ENOMEM;
 
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	efuse->iomem = devm_ioremap(&pdev->dev, res->start, resource_size(res));
-	if (IS_ERR(efuse->iomem))
-		return PTR_ERR(efuse->iomem);
+	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, "bus_clk");
+	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);
+
+	efuse->dev = dev;
 	/*
 	 * rd_adj and rd_strobe are 4 bit values
 	 * bus clk period * (rd_adj + 1) > 6.5ns
@@ -204,12 +186,18 @@ static int jz4780_efuse_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "Cannot set clock configuration\n");
 		return -EINVAL;
 	}
-	efuse->dev = dev;
 
-	jz4780_efuse_nvmem_config.dev = &pdev->dev;
-	jz4780_efuse_nvmem_config.priv = efuse;
+	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 = nvmem_register(&jz4780_efuse_nvmem_config);
+	nvmem = nvmem_register(&cfg);
 	if (IS_ERR(nvmem))
 		return PTR_ERR(nvmem);
 
@@ -245,5 +233,6 @@ 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

[RFC v3 3/9] Bindings: nvmem: add bindings for JZ4780 efuse

[H. Nikolaus Schaller]

From: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>

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

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>
---
 .../bindings/nvmem/ingenic,jz4780-efuse.txt     | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/nvmem/ingenic,jz4780-efuse.txt

diff --git a/Documentation/devicetree/bindings/nvmem/ingenic,jz4780-efuse.txt b/Documentation/devicetree/bindings/nvmem/ingenic,jz4780-efuse.txt
new file mode 100644
index 000000000000..339e74daa9a9
--- /dev/null
+++ b/Documentation/devicetree/bindings/nvmem/ingenic,jz4780-efuse.txt
@@ -0,0 +1,17 @@
+Ingenic JZ EFUSE driver bindings
+
+Required properties:
+- "compatible"		Must be set to "ingenic,jz4780-efuse"
+- "reg"			Register location and length
+- "clocks"		Handle for the ahb clock for the efuse.
+- "clock-names"		Must be "bus_clk"
+
+Example:
+
+efuse: efuse@134100d0 {
+	compatible = "ingenic,jz4780-efuse";
+	reg = <0x134100d0 0x2c>;
+
+	clocks = <&cgu JZ4780_CLK_AHB2>;
+	clock-names = "bus_clk";
+};
-- 
2.23.0

[RFC v3 4/9] Documentation: ABI: nvmem: add documentation for JZ4780 efuse ABI

[H. Nikolaus Schaller]

From: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>

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

Tested-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: Mathieu Malaterre <malat@debian.org>
---
 .../ABI/testing/sysfs-driver-jz4780-efuse        | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-driver-jz4780-efuse

diff --git a/Documentation/ABI/testing/sysfs-driver-jz4780-efuse b/Documentation/ABI/testing/sysfs-driver-jz4780-efuse
new file mode 100644
index 000000000000..bb6f5d6ceea0
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-jz4780-efuse
@@ -0,0 +1,16 @@
+What:		/sys/devices/*/<our-device>/nvmem
+Date:		December 2017
+Contact:	PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
+Description:	read-only access to the efuse on the Ingenic JZ4780 SoC
+		The SoC has a one time programmable 8K efuse that is
+		split into segments. The driver supports read only.
+		The segments are
+		0x000   64 bit Random Number
+		0x008  128 bit Ingenic Chip ID
+		0x018  128 bit Customer ID
+		0x028 3520 bit Reserved
+		0x1E0    8 bit Protect Segment
+		0x1E1 2296 bit HDMI Key
+		0x300 2048 bit Security boot key
+Users:		any user space application which wants to read the Chip
+		and Customer ID
-- 
2.23.0

[RFC v3 5/9] nvmem: MAINTAINERS: add maintainer for JZ4780 efuse driver

[H. Nikolaus Schaller]

From: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>

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

Tested-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: Mathieu Malaterre <malat@debian.org>
---
 MAINTAINERS | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 33f811f517d4..88f247456a48 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8270,6 +8270,11 @@ M:	Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
 S:	Maintained
 F:	drivers/dma/dma-jz4780.c
 
+INGENIC JZ4780 EFUSE Driver
+M:	PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
+S:	Maintained
+F:	drivers/nvmem/jz4780-efuse.c
+
 INGENIC JZ4780 NAND DRIVER
 M:	Harvey Hunt <harveyhuntnexus@gmail.com>
 L:	linux-mtd@lists.infradead.org
-- 
2.23.0

[RFC v3 6/9] MIPS: DTS: JZ4780: define node for JZ4780 efuse

[H. Nikolaus Schaller]

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 the
ethernet mac address for the davicom dm9000 chip on the CI20 board.

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>
---
 arch/mips/boot/dts/ingenic/jz4780.dtsi | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/mips/boot/dts/ingenic/jz4780.dtsi b/arch/mips/boot/dts/ingenic/jz4780.dtsi
index 301b62da025e..4cc8abe675c2 100644
--- a/arch/mips/boot/dts/ingenic/jz4780.dtsi
+++ b/arch/mips/boot/dts/ingenic/jz4780.dtsi
@@ -393,7 +393,7 @@
 
 	nemc: nemc@13410000 {
 		compatible = "ingenic,jz4780-nemc";
-		reg = <0x13410000 0x10000>;
+		reg = <0x13410000 0x4c>;
 		#address-cells = <2>;
 		#size-cells = <1>;
 		ranges = <1 0 0x1b000000 0x1000000
@@ -408,6 +408,21 @@
 		status = "disabled";
 	};
 
+	efuse: efuse@134100d0 {
+		compatible = "ingenic,jz4780-efuse";
+		reg = <0x134100d0 0x2c>;
+
+		clocks = <&cgu JZ4780_CLK_AHB2>;
+		clock-names = "bus_clk";
+
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		eth0_addr: eth-mac-addr@0x22 {
+			reg = <0x22 0x6>;
+		};
+	};
+
 	dma: dma@13420000 {
 		compatible = "ingenic,jz4780-dma";
 		reg = <0x13420000 0x400
-- 
2.23.0

[RFC v3 7/9] MIPS: DTS: CI20: make DM9000 Ethernet controller use NVMEM to find the default MAC address

[H. Nikolaus Schaller]

There is a default MAC address factory programmed into
the eFuses of the JZ4780 chip. By using this every CI20
board has an individual but stable MAC address and DHCP
can assing stable IP addresses.

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
---
 arch/mips/boot/dts/ingenic/ci20.dts | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/mips/boot/dts/ingenic/ci20.dts b/arch/mips/boot/dts/ingenic/ci20.dts
index 1166f3203ff8..63b4b53b5df5 100644
--- a/arch/mips/boot/dts/ingenic/ci20.dts
+++ b/arch/mips/boot/dts/ingenic/ci20.dts
@@ -428,6 +428,9 @@ Optional input supply properties:
 
 		interrupt-parent = <&gpe>;
 		interrupts = <19 4>;
+
+		nvmem-cells = <&eth0_addr>;
+		nvmem-cell-names = "mac-address";
 	};
 };
 
-- 
2.23.0

[RFC v3 8/9] MIPS: CI20 defconfig: Probe efuse for CI20

[H. Nikolaus Schaller]

From: Mathieu Malaterre <malat@debian.org>

MIPS Creator CI20 comes with JZ4780 SoC. Provides access to the efuse block
using jz4780 efuse driver.

Tested-by: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Mathieu Malaterre <malat@debian.org>
---
 arch/mips/configs/ci20_defconfig | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/mips/configs/ci20_defconfig b/arch/mips/configs/ci20_defconfig
index 6e613bbb6807..614dc18211bc 100644
--- a/arch/mips/configs/ci20_defconfig
+++ b/arch/mips/configs/ci20_defconfig
@@ -193,3 +193,5 @@ CONFIG_RC_DEVICES=y
 CONFIG_IR_GPIO_CIR=m
 CONFIG_IR_GPIO_TX=m
 CONFIG_RTC_DRV_PCF8563=m
+CONFIG_NVMEM=y
+CONFIG_JZ4780_EFUSE=y
-- 
2.23.0

[RFC v3 9/9] MIPS: CI20 defconfig: DEMO HACK: make DM9000 a module

[H. Nikolaus Schaller]

It appears that reading the ethernet mac address from NVMEM,
i.e. through the jz4780-efuse driver, requires the jz4780-efuse
driver to be up and running before the dm9000 driver is probed.

This is because there is a registration mechanism for nvmem
devices and consumers scan the global table. If the provider
has not yet been registered, the required matching entry
is not found and the consumer assumes there is no nvram.

In the case of the dm9000 it will not wait but assign a
random MAC address.

It appears that if the dm9000 is configured into the kernel
binary, it will be probed first and the correct sequence is
broken.

If it is a module (or even both), the way deferred probing
works seems to serialize properly.

So this hack is for demo purposes only and makes the dm9000
probing being delayed.

A proper solution is to make sure the jz4780-efuse driver
is probed earlier than the dm9000 driver (or mac address
lookup).

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
---
 arch/mips/configs/ci20_defconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/configs/ci20_defconfig b/arch/mips/configs/ci20_defconfig
index 614dc18211bc..1d3d1d9b62bc 100644
--- a/arch/mips/configs/ci20_defconfig
+++ b/arch/mips/configs/ci20_defconfig
@@ -59,7 +59,7 @@ CONFIG_MTD_UBI_FASTMAP=y
 CONFIG_NETDEVICES=y
 # CONFIG_NET_VENDOR_ARC is not set
 # CONFIG_NET_VENDOR_BROADCOM is not set
-CONFIG_DM9000=y
+CONFIG_DM9000=m
 CONFIG_DM9000_FORCE_SIMPLE_PHY_POLL=y
 # CONFIG_NET_VENDOR_INTEL is not set
 # CONFIG_NET_VENDOR_MARVELL is not set
-- 
2.23.0

Re: [RFC v3 1/9] nvmem: add driver for JZ4780 efuse

[Srinivas Kandagatla]

On 16/02/2020 19:20, H. Nikolaus Schaller wrote:
> 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 | 249 +++++++++++++++++++++++++++++++++++
>   3 files changed, 261 insertions(+)
>   create mode 100644 drivers/nvmem/jz4780-efuse.c
> 

This patch along with 2/9 should be merged into single patch.
Also please make sure you run checkpatch.pl before sending!

> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> index 35efab1ba8d9..10f8e08f5e31 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_JZ4780 || COMPILE_TEST

what is that this driver depends on MACH_JZ4780 board?


> +	depends on HAS_IOMEM
> +	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..ac03e1900ef9
> --- /dev/null
> +++ b/drivers/nvmem/jz4780-efuse.c
> @@ -0,0 +1,249 @@
> +// 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>
?? why do we need these two headers in this patch


> +
> +#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 JZ_EFUSE_START_ADDR		0x200
> +
> +#define JZ_EFUSE_EFUCTRL_CS		BIT(30)
> +#define JZ_EFUSE_EFUCTRL_ADDR_MASK	0x1FF
> +#define JZ_EFUSE_EFUCTRL_ADDR_SHIFT	21
> +#define JZ_EFUSE_EFUCTRL_LEN_MASK	0x1F
> +#define JZ_EFUSE_EFUCTRL_LEN_SHIFT	16
> +#define JZ_EFUSE_EFUCTRL_PG_EN		BIT(15)
> +#define JZ_EFUSE_EFUCTRL_WR_EN		BIT(1)
> +#define JZ_EFUSE_EFUCTRL_RD_EN		BIT(0)
> +
> +#define JZ_EFUSE_EFUCFG_INT_EN		BIT(31)
> +#define JZ_EFUSE_EFUCFG_RD_ADJ_MASK	0xF

consider using GENMASK for these masks here.

> +#define JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT	20
> +#define JZ_EFUSE_EFUCFG_RD_STR_MASK	0xF
> +#define JZ_EFUSE_EFUCFG_RD_STR_SHIFT	16
> +#define JZ_EFUSE_EFUCFG_WR_ADJ_MASK	0xF
> +#define JZ_EFUSE_EFUCFG_WR_ADJ_SHIFT	12
> +#define JZ_EFUSE_EFUCFG_WR_STR_MASK	0xFFF
> +#define JZ_EFUSE_EFUCFG_WR_STR_SHIFT	0
> +
> +#define JZ_EFUSE_EFUSTATE_WR_DONE	BIT(1)
> +#define JZ_EFUSE_EFUSTATE_RD_DONE	BIT(0)
> +
> +struct jz4780_efuse {
> +	struct device *dev;
> +	void __iomem *iomem;
> +	struct clk *clk;
> +	unsigned int rd_adj;
> +	unsigned int rd_strobe;
> +};
> +
> +/* We read 32 byte chunks to avoid complexity in the driver. */
> +static int jz4780_efuse_read_32bytes(struct jz4780_efuse *efuse, char *buf,
> +		unsigned int addr)
> +{
> +	unsigned int tmp = 0;
> +	int i = 0;

unnecessary initialization of both variables.

> +	int timeout = 1000;
> +	int size = 32;

better to #define this STRIDE/CHUNK size. this driver seems to use this 
value in multiple places.

> +
> +	/* 1. Set config register */
> +	tmp = readl(efuse->iomem + JZ_EFUCFG);
> +	tmp &= ~((JZ_EFUSE_EFUCFG_RD_ADJ_MASK << JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
> +	| (JZ_EFUSE_EFUCFG_RD_STR_MASK << JZ_EFUSE_EFUCFG_RD_STR_SHIFT));
> +	tmp |= (efuse->rd_adj << JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
> +	| (efuse->rd_strobe << JZ_EFUSE_EFUCFG_RD_STR_SHIFT);

very odd indenting.

> +	writel(tmp, efuse->iomem + JZ_EFUCFG);
> +
> +	/*
> +	 * 2. Set control register to indicate what to read data address,
> +	 * read data numbers and read enable.
> +	 */
> +	tmp = readl(efuse->iomem + JZ_EFUCTRL);
> +	tmp &= ~(JZ_EFUSE_EFUCFG_RD_STR_SHIFT
> +		| (JZ_EFUSE_EFUCTRL_ADDR_MASK << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
> +		| JZ_EFUSE_EFUCTRL_PG_EN | JZ_EFUSE_EFUCTRL_WR_EN
> +		| JZ_EFUSE_EFUCTRL_WR_EN);
> +
> +	/* Need to select CS bit if address accesses upper 4Kbits memory */
> +	if (addr >= (JZ_EFUSE_START_ADDR + 512))
> +		tmp |= JZ_EFUSE_EFUCTRL_CS;
> +
> +	tmp |= (addr << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
> +		| ((size - 1) << JZ_EFUSE_EFUCTRL_LEN_SHIFT)
> +		| JZ_EFUSE_EFUCTRL_RD_EN;
> +	writel(tmp, efuse->iomem + JZ_EFUCTRL);
> +
> +	/*
> +	 * 3. Wait status register RD_DONE set to 1 or EFUSE interrupted,
> +	 * software can read EFUSE data buffer 0 - 8 registers.
> +	 */
> +	do {
> +		tmp = readl(efuse->iomem + JZ_EFUSTATE);
> +		usleep_range(1000, 2000);
> +		if (timeout--)
> +			break;
> +	} while (!(tmp & JZ_EFUSE_EFUSTATE_RD_DONE));
> +
> +	if (timeout <= 0) {
> +		dev_err(efuse->dev, "Timed out while reading\n");
> +		return -EAGAIN;
> +	}
> +
> +	for (i = 0; i < (size / 4); i++)
> +		*((unsigned int *)(buf + i * 4))

make "unsigned int *buf32" a local variable and use it here, makes it 
much readable code.

> +			 = readl(efuse->iomem + JZ_EFUDATA(i));
> +
> +	return 0;
> +}
> +
> +/* 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;
> +
> +	while (bytes > 0) {
> +		unsigned int start = offset & ~(32 - 1);
> +		unsigned chunk = min(bytes, (start + 32 - offset));
> +
> +		if (start == offset && chunk == 32) {
> +			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);
> +		}
> +
> +		val += chunk;
> +		offset += chunk;
> +		bytes -= chunk;
> +	}
> +
> +	return 0;
> +}
> +
> +static struct nvmem_config jz4780_efuse_nvmem_config = {
> +	.name = "jz4780-efuse",
> +	.read_only = true,

this value comes from device tree bindings, do we still need  to specify 
this here?


> +	.size = 1024,
> +	.word_size = 1,
> +	.stride = 1,
> +	.owner = THIS_MODULE,
> +	.reg_read = jz4780_efuse_read,
> +};
> +
> +static int jz4780_efuse_probe(struct platform_device *pdev)
> +{
> +	struct nvmem_device *nvmem;
> +	struct jz4780_efuse *efuse;
> +	struct resource *res;
> +	unsigned long clk_rate;
> +	struct device *dev = &pdev->dev;
> +
> +	efuse = devm_kzalloc(&pdev->dev, sizeof(*efuse), GFP_KERNEL);
> +	if (!efuse)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	efuse->iomem = devm_ioremap(&pdev->dev, res->start, resource_size(res));
> +	if (IS_ERR(efuse->iomem))
> +		return PTR_ERR(efuse->iomem);
> +
> +	efuse->clk = devm_clk_get(&pdev->dev, "bus_clk");
> +	if (IS_ERR(efuse->clk))
> +		return PTR_ERR(efuse->clk);

Who is enabling this clk?


> +
> +	clk_rate = clk_get_rate(efuse->clk);
> +	/*
> +	 * 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;
> +	efuse->rd_strobe = ((((35000 * (clk_rate / 1000000)) / 1000000) + 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;
> +	}
> +	efuse->dev = dev;
> +
> +	jz4780_efuse_nvmem_config.dev = &pdev->dev;
> +	jz4780_efuse_nvmem_config.priv = efuse;
> +
> +	nvmem = nvmem_register(&jz4780_efuse_nvmem_config);

devm variant here?


> +	if (IS_ERR(nvmem))
> +		return PTR_ERR(nvmem);
> +
> +	platform_set_drvdata(pdev, nvmem);
> +
> +	return 0;
> +}
> +
> +static int jz4780_efuse_remove(struct platform_device *pdev)
> +{
> +	struct nvmem_device *nvmem = platform_get_drvdata(pdev);
> +
> +	nvmem_unregister(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,
> +	.remove = jz4780_efuse_remove,
> +	.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_DESCRIPTION("Ingenic JZ4780 efuse driver");
> +MODULE_LICENSE("GPL v2");
> 

Re: [RFC v3 1/9] nvmem: add driver for JZ4780 efuse

[H. Nikolaus Schaller]

Hi Srinivas Kandagatla,

> Am 17.02.2020 um 12:36 schrieb Srinivas Kandagatla <srinivas.kandagatla@linaro.org>:
> 
> 
> 
> On 16/02/2020 19:20, H. Nikolaus Schaller wrote:
>> 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>)

@Paul: may I assume your signed off after squashing the patch 2/9?

>> ---
>>  drivers/nvmem/Kconfig        |  10 ++
>>  drivers/nvmem/Makefile       |   2 +
>>  drivers/nvmem/jz4780-efuse.c | 249 +++++++++++++++++++++++++++++++++++
>>  3 files changed, 261 insertions(+)
>>  create mode 100644 drivers/nvmem/jz4780-efuse.c
> 
> This patch along with 2/9 should be merged into single patch.
> Also please make sure you run checkpatch.pl before sending!

Sure. I had noted that in the [0/9].

> 
>> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
>> index 35efab1ba8d9..10f8e08f5e31 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_JZ4780 || COMPILE_TEST
> 
> what is that this driver depends on MACH_JZ4780 board?

Hm. Good question. Well, it is only useful for the jz4780 SoC
but since we match drivers through DTS there is probably no reason
to make it depend on. And depend on COMPILE_TEST is also not
needed if I understand correctly.

On the other hand this makes the option disappear for non-jz4780 SoC.

So I leave it for the moment but keep in mind.

> 
> 
>> +	depends on HAS_IOMEM
>> +	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..ac03e1900ef9
>> --- /dev/null
>> +++ b/drivers/nvmem/jz4780-efuse.c
>> @@ -0,0 +1,249 @@
>> +// 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>
> ?? why do we need these two headers in this patch

regmap will be used after squashing 2/9.

> 
> 
>> +
>> +#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 JZ_EFUSE_START_ADDR		0x200
>> +
>> +#define JZ_EFUSE_EFUCTRL_CS		BIT(30)
>> +#define JZ_EFUSE_EFUCTRL_ADDR_MASK	0x1FF
>> +#define JZ_EFUSE_EFUCTRL_ADDR_SHIFT	21
>> +#define JZ_EFUSE_EFUCTRL_LEN_MASK	0x1F
>> +#define JZ_EFUSE_EFUCTRL_LEN_SHIFT	16
>> +#define JZ_EFUSE_EFUCTRL_PG_EN		BIT(15)
>> +#define JZ_EFUSE_EFUCTRL_WR_EN		BIT(1)
>> +#define JZ_EFUSE_EFUCTRL_RD_EN		BIT(0)
>> +
>> +#define JZ_EFUSE_EFUCFG_INT_EN		BIT(31)
>> +#define JZ_EFUSE_EFUCFG_RD_ADJ_MASK	0xF
> 
> consider using GENMASK for these masks here.
> 
>> +#define JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT	20
>> +#define JZ_EFUSE_EFUCFG_RD_STR_MASK	0xF
>> +#define JZ_EFUSE_EFUCFG_RD_STR_SHIFT	16
>> +#define JZ_EFUSE_EFUCFG_WR_ADJ_MASK	0xF
>> +#define JZ_EFUSE_EFUCFG_WR_ADJ_SHIFT	12
>> +#define JZ_EFUSE_EFUCFG_WR_STR_MASK	0xFFF
>> +#define JZ_EFUSE_EFUCFG_WR_STR_SHIFT	0
>> +
>> +#define JZ_EFUSE_EFUSTATE_WR_DONE	BIT(1)
>> +#define JZ_EFUSE_EFUSTATE_RD_DONE	BIT(0)
>> +
>> +struct jz4780_efuse {
>> +	struct device *dev;
>> +	void __iomem *iomem;
>> +	struct clk *clk;
>> +	unsigned int rd_adj;
>> +	unsigned int rd_strobe;
>> +};
>> +
>> +/* We read 32 byte chunks to avoid complexity in the driver. */
>> +static int jz4780_efuse_read_32bytes(struct jz4780_efuse *efuse, char *buf,
>> +		unsigned int addr)
>> +{
>> +	unsigned int tmp = 0;
>> +	int i = 0;
> 
> unnecessary initialization of both variables.
> 
>> +	int timeout = 1000;
>> +	int size = 32;
> 
> better to #define this STRIDE/CHUNK size. this driver seems to use this value in multiple places.
> 
>> +
>> +	/* 1. Set config register */
>> +	tmp = readl(efuse->iomem + JZ_EFUCFG);
>> +	tmp &= ~((JZ_EFUSE_EFUCFG_RD_ADJ_MASK << JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
>> +	| (JZ_EFUSE_EFUCFG_RD_STR_MASK << JZ_EFUSE_EFUCFG_RD_STR_SHIFT));
>> +	tmp |= (efuse->rd_adj << JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
>> +	| (efuse->rd_strobe << JZ_EFUSE_EFUCFG_RD_STR_SHIFT);
> 
> very odd indenting.

Will be replaced by 2/9.

Sorry for having you review this old version which is replaced by 2/9.

But it appeared more helpful to keep this as the 2018 original and then update
in a separate patch for this RFC stage.

> 
>> +	writel(tmp, efuse->iomem + JZ_EFUCFG);
>> +
>> +	/*
>> +	 * 2. Set control register to indicate what to read data address,
>> +	 * read data numbers and read enable.
>> +	 */
>> +	tmp = readl(efuse->iomem + JZ_EFUCTRL);
>> +	tmp &= ~(JZ_EFUSE_EFUCFG_RD_STR_SHIFT
>> +		| (JZ_EFUSE_EFUCTRL_ADDR_MASK << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
>> +		| JZ_EFUSE_EFUCTRL_PG_EN | JZ_EFUSE_EFUCTRL_WR_EN
>> +		| JZ_EFUSE_EFUCTRL_WR_EN);
>> +
>> +	/* Need to select CS bit if address accesses upper 4Kbits memory */
>> +	if (addr >= (JZ_EFUSE_START_ADDR + 512))
>> +		tmp |= JZ_EFUSE_EFUCTRL_CS;
>> +
>> +	tmp |= (addr << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
>> +		| ((size - 1) << JZ_EFUSE_EFUCTRL_LEN_SHIFT)
>> +		| JZ_EFUSE_EFUCTRL_RD_EN;
>> +	writel(tmp, efuse->iomem + JZ_EFUCTRL);
>> +
>> +	/*
>> +	 * 3. Wait status register RD_DONE set to 1 or EFUSE interrupted,
>> +	 * software can read EFUSE data buffer 0 - 8 registers.
>> +	 */
>> +	do {
>> +		tmp = readl(efuse->iomem + JZ_EFUSTATE);
>> +		usleep_range(1000, 2000);
>> +		if (timeout--)
>> +			break;
>> +	} while (!(tmp & JZ_EFUSE_EFUSTATE_RD_DONE));
>> +
>> +	if (timeout <= 0) {
>> +		dev_err(efuse->dev, "Timed out while reading\n");
>> +		return -EAGAIN;
>> +	}
>> +
>> +	for (i = 0; i < (size / 4); i++)
>> +		*((unsigned int *)(buf + i * 4))
> 
> make "unsigned int *buf32" a local variable and use it here, makes it much readable code.
> 
>> +			 = readl(efuse->iomem + JZ_EFUDATA(i));
>> +
>> +	return 0;
>> +}
>> +
>> +/* 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;
>> +
>> +	while (bytes > 0) {
>> +		unsigned int start = offset & ~(32 - 1);
>> +		unsigned chunk = min(bytes, (start + 32 - offset));
>> +
>> +		if (start == offset && chunk == 32) {
>> +			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);
>> +		}
>> +
>> +		val += chunk;
>> +		offset += chunk;
>> +		bytes -= chunk;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static struct nvmem_config jz4780_efuse_nvmem_config = {
>> +	.name = "jz4780-efuse",
>> +	.read_only = true,
> 
> this value comes from device tree bindings, do we still need  to specify this here?

Ok, have to check what is automatically taken from DT.

> 
> 
>> +	.size = 1024,
>> +	.word_size = 1,
>> +	.stride = 1,
>> +	.owner = THIS_MODULE,
>> +	.reg_read = jz4780_efuse_read,
>> +};
>> +
>> +static int jz4780_efuse_probe(struct platform_device *pdev)
>> +{
>> +	struct nvmem_device *nvmem;
>> +	struct jz4780_efuse *efuse;
>> +	struct resource *res;
>> +	unsigned long clk_rate;
>> +	struct device *dev = &pdev->dev;
>> +
>> +	efuse = devm_kzalloc(&pdev->dev, sizeof(*efuse), GFP_KERNEL);
>> +	if (!efuse)
>> +		return -ENOMEM;
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	efuse->iomem = devm_ioremap(&pdev->dev, res->start, resource_size(res));
>> +	if (IS_ERR(efuse->iomem))
>> +		return PTR_ERR(efuse->iomem);
>> +
>> +	efuse->clk = devm_clk_get(&pdev->dev, "bus_clk");
>> +	if (IS_ERR(efuse->clk))
>> +		return PTR_ERR(efuse->clk);
> 
> Who is enabling this clk?
> 
> 
>> +
>> +	clk_rate = clk_get_rate(efuse->clk);
>> +	/*
>> +	 * 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;
>> +	efuse->rd_strobe = ((((35000 * (clk_rate / 1000000)) / 1000000) + 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;
>> +	}
>> +	efuse->dev = dev;
>> +
>> +	jz4780_efuse_nvmem_config.dev = &pdev->dev;
>> +	jz4780_efuse_nvmem_config.priv = efuse;
>> +
>> +	nvmem = nvmem_register(&jz4780_efuse_nvmem_config);
> 
> devm variant here?

Good idea! I didn't know that it exists. Allows us to remove
jz4780_efuse_remove() below.
 
> 
> 
>> +	if (IS_ERR(nvmem))
>> +		return PTR_ERR(nvmem);
>> +
>> +	platform_set_drvdata(pdev, nvmem);
>> +
>> +	return 0;
>> +}
>> +
>> +static int jz4780_efuse_remove(struct platform_device *pdev)
>> +{
>> +	struct nvmem_device *nvmem = platform_get_drvdata(pdev);
>> +
>> +	nvmem_unregister(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,
>> +	.remove = jz4780_efuse_remove,
>> +	.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_DESCRIPTION("Ingenic JZ4780 efuse driver");
>> +MODULE_LICENSE("GPL v2");

BR and thanks,
Nikolaus Schaller

Re: [RFC v3 1/9] nvmem: add driver for JZ4780 efuse

[Paul Cercueil]

Hi Nikolaus,


Le lun., févr. 17, 2020 at 13:26, H. Nikolaus Schaller 
<hns@goldelico.com> a écrit :
> Hi Srinivas Kandagatla,
> 
>>  Am 17.02.2020 um 12:36 schrieb Srinivas Kandagatla 
>> <srinivas.kandagatla@linaro.org>:
>> 
>> 
>> 
>>  On 16/02/2020 19:20, H. Nikolaus Schaller wrote:
>>>  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>)
> 
> @Paul: may I assume your signed off after squashing the patch 2/9?

Yes. As the Ingenic SoCs maintainer I'll still need to review though.

> 
>>>  ---
>>>   drivers/nvmem/Kconfig        |  10 ++
>>>   drivers/nvmem/Makefile       |   2 +
>>>   drivers/nvmem/jz4780-efuse.c | 249 
>>> +++++++++++++++++++++++++++++++++++
>>>   3 files changed, 261 insertions(+)
>>>   create mode 100644 drivers/nvmem/jz4780-efuse.c
>> 
>>  This patch along with 2/9 should be merged into single patch.
>>  Also please make sure you run checkpatch.pl before sending!
> 
> Sure. I had noted that in the [0/9].
> 
>> 
>>>  diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
>>>  index 35efab1ba8d9..10f8e08f5e31 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_JZ4780 || COMPILE_TEST
>> 
>>  what is that this driver depends on MACH_JZ4780 board?
> 
> Hm. Good question. Well, it is only useful for the jz4780 SoC
> but since we match drivers through DTS there is probably no reason
> to make it depend on. And depend on COMPILE_TEST is also not
> needed if I understand correctly.
> 
> On the other hand this makes the option disappear for non-jz4780 SoC.
> 
> So I leave it for the moment but keep in mind.

Make it MACH_INGENIC || COMPILE_TEST.

* You want COMPILE_TEST so that the driver can be compile-tested. It 
should always be there unless the driver really isn't buildable if 
MACH_JZ4780 is not set.
* If you depend on MACH_JZ4780, then you cannot create a kernel that 
will work on anything else than a JZ4780. Depend on MACH_INGENIC 
instead.

> 
>> 
>> 
>>>  +	depends on HAS_IOMEM
>>>  +	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..ac03e1900ef9
>>>  --- /dev/null
>>>  +++ b/drivers/nvmem/jz4780-efuse.c
>>>  @@ -0,0 +1,249 @@
>>>  +// 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>
>>  ?? why do we need these two headers in this patch
> 
> regmap will be used after squashing 2/9.
> 
>> 
>> 
>>>  +
>>>  +#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 JZ_EFUSE_START_ADDR		0x200
>>>  +
>>>  +#define JZ_EFUSE_EFUCTRL_CS		BIT(30)
>>>  +#define JZ_EFUSE_EFUCTRL_ADDR_MASK	0x1FF
>>>  +#define JZ_EFUSE_EFUCTRL_ADDR_SHIFT	21
>>>  +#define JZ_EFUSE_EFUCTRL_LEN_MASK	0x1F
>>>  +#define JZ_EFUSE_EFUCTRL_LEN_SHIFT	16
>>>  +#define JZ_EFUSE_EFUCTRL_PG_EN		BIT(15)
>>>  +#define JZ_EFUSE_EFUCTRL_WR_EN		BIT(1)
>>>  +#define JZ_EFUSE_EFUCTRL_RD_EN		BIT(0)
>>>  +
>>>  +#define JZ_EFUSE_EFUCFG_INT_EN		BIT(31)
>>>  +#define JZ_EFUSE_EFUCFG_RD_ADJ_MASK	0xF
>> 
>>  consider using GENMASK for these masks here.
>> 
>>>  +#define JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT	20
>>>  +#define JZ_EFUSE_EFUCFG_RD_STR_MASK	0xF
>>>  +#define JZ_EFUSE_EFUCFG_RD_STR_SHIFT	16
>>>  +#define JZ_EFUSE_EFUCFG_WR_ADJ_MASK	0xF
>>>  +#define JZ_EFUSE_EFUCFG_WR_ADJ_SHIFT	12
>>>  +#define JZ_EFUSE_EFUCFG_WR_STR_MASK	0xFFF
>>>  +#define JZ_EFUSE_EFUCFG_WR_STR_SHIFT	0
>>>  +
>>>  +#define JZ_EFUSE_EFUSTATE_WR_DONE	BIT(1)
>>>  +#define JZ_EFUSE_EFUSTATE_RD_DONE	BIT(0)
>>>  +
>>>  +struct jz4780_efuse {
>>>  +	struct device *dev;
>>>  +	void __iomem *iomem;
>>>  +	struct clk *clk;
>>>  +	unsigned int rd_adj;
>>>  +	unsigned int rd_strobe;
>>>  +};
>>>  +
>>>  +/* We read 32 byte chunks to avoid complexity in the driver. */
>>>  +static int jz4780_efuse_read_32bytes(struct jz4780_efuse *efuse, 
>>> char *buf,
>>>  +		unsigned int addr)
>>>  +{
>>>  +	unsigned int tmp = 0;
>>>  +	int i = 0;
>> 
>>  unnecessary initialization of both variables.
>> 
>>>  +	int timeout = 1000;
>>>  +	int size = 32;
>> 
>>  better to #define this STRIDE/CHUNK size. this driver seems to use 
>> this value in multiple places.
>> 
>>>  +
>>>  +	/* 1. Set config register */
>>>  +	tmp = readl(efuse->iomem + JZ_EFUCFG);
>>>  +	tmp &= ~((JZ_EFUSE_EFUCFG_RD_ADJ_MASK << 
>>> JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
>>>  +	| (JZ_EFUSE_EFUCFG_RD_STR_MASK << JZ_EFUSE_EFUCFG_RD_STR_SHIFT));
>>>  +	tmp |= (efuse->rd_adj << JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
>>>  +	| (efuse->rd_strobe << JZ_EFUSE_EFUCFG_RD_STR_SHIFT);
>> 
>>  very odd indenting.
> 
> Will be replaced by 2/9.
> 
> Sorry for having you review this old version which is replaced by 2/9.
> 
> But it appeared more helpful to keep this as the 2018 original and 
> then update
> in a separate patch for this RFC stage.
> 
>> 
>>>  +	writel(tmp, efuse->iomem + JZ_EFUCFG);
>>>  +
>>>  +	/*
>>>  +	 * 2. Set control register to indicate what to read data address,
>>>  +	 * read data numbers and read enable.
>>>  +	 */
>>>  +	tmp = readl(efuse->iomem + JZ_EFUCTRL);
>>>  +	tmp &= ~(JZ_EFUSE_EFUCFG_RD_STR_SHIFT
>>>  +		| (JZ_EFUSE_EFUCTRL_ADDR_MASK << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
>>>  +		| JZ_EFUSE_EFUCTRL_PG_EN | JZ_EFUSE_EFUCTRL_WR_EN
>>>  +		| JZ_EFUSE_EFUCTRL_WR_EN);
>>>  +
>>>  +	/* Need to select CS bit if address accesses upper 4Kbits memory 
>>> */
>>>  +	if (addr >= (JZ_EFUSE_START_ADDR + 512))
>>>  +		tmp |= JZ_EFUSE_EFUCTRL_CS;
>>>  +
>>>  +	tmp |= (addr << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
>>>  +		| ((size - 1) << JZ_EFUSE_EFUCTRL_LEN_SHIFT)
>>>  +		| JZ_EFUSE_EFUCTRL_RD_EN;
>>>  +	writel(tmp, efuse->iomem + JZ_EFUCTRL);
>>>  +
>>>  +	/*
>>>  +	 * 3. Wait status register RD_DONE set to 1 or EFUSE interrupted,
>>>  +	 * software can read EFUSE data buffer 0 - 8 registers.
>>>  +	 */
>>>  +	do {
>>>  +		tmp = readl(efuse->iomem + JZ_EFUSTATE);
>>>  +		usleep_range(1000, 2000);
>>>  +		if (timeout--)
>>>  +			break;
>>>  +	} while (!(tmp & JZ_EFUSE_EFUSTATE_RD_DONE));
>>>  +
>>>  +	if (timeout <= 0) {
>>>  +		dev_err(efuse->dev, "Timed out while reading\n");
>>>  +		return -EAGAIN;
>>>  +	}
>>>  +
>>>  +	for (i = 0; i < (size / 4); i++)
>>>  +		*((unsigned int *)(buf + i * 4))
>> 
>>  make "unsigned int *buf32" a local variable and use it here, makes 
>> it much readable code.
>> 
>>>  +			 = readl(efuse->iomem + JZ_EFUDATA(i));
>>>  +
>>>  +	return 0;
>>>  +}
>>>  +
>>>  +/* 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;
>>>  +
>>>  +	while (bytes > 0) {
>>>  +		unsigned int start = offset & ~(32 - 1);
>>>  +		unsigned chunk = min(bytes, (start + 32 - offset));
>>>  +
>>>  +		if (start == offset && chunk == 32) {
>>>  +			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);
>>>  +		}
>>>  +
>>>  +		val += chunk;
>>>  +		offset += chunk;
>>>  +		bytes -= chunk;
>>>  +	}
>>>  +
>>>  +	return 0;
>>>  +}
>>>  +
>>>  +static struct nvmem_config jz4780_efuse_nvmem_config = {
>>>  +	.name = "jz4780-efuse",
>>>  +	.read_only = true,
>> 
>>  this value comes from device tree bindings, do we still need  to 
>> specify this here?
> 
> Ok, have to check what is automatically taken from DT.
> 
>> 
>> 
>>>  +	.size = 1024,
>>>  +	.word_size = 1,
>>>  +	.stride = 1,
>>>  +	.owner = THIS_MODULE,
>>>  +	.reg_read = jz4780_efuse_read,
>>>  +};
>>>  +
>>>  +static int jz4780_efuse_probe(struct platform_device *pdev)
>>>  +{
>>>  +	struct nvmem_device *nvmem;
>>>  +	struct jz4780_efuse *efuse;
>>>  +	struct resource *res;
>>>  +	unsigned long clk_rate;
>>>  +	struct device *dev = &pdev->dev;
>>>  +
>>>  +	efuse = devm_kzalloc(&pdev->dev, sizeof(*efuse), GFP_KERNEL);
>>>  +	if (!efuse)
>>>  +		return -ENOMEM;
>>>  +
>>>  +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>>  +	efuse->iomem = devm_ioremap(&pdev->dev, res->start, 
>>> resource_size(res));
>>>  +	if (IS_ERR(efuse->iomem))
>>>  +		return PTR_ERR(efuse->iomem);
>>>  +
>>>  +	efuse->clk = devm_clk_get(&pdev->dev, "bus_clk");
>>>  +	if (IS_ERR(efuse->clk))
>>>  +		return PTR_ERR(efuse->clk);
>> 
>>  Who is enabling this clk?
>> 
>> 
>>>  +
>>>  +	clk_rate = clk_get_rate(efuse->clk);
>>>  +	/*
>>>  +	 * 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;
>>>  +	efuse->rd_strobe = ((((35000 * (clk_rate / 1000000)) / 1000000) 
>>> + 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;
>>>  +	}
>>>  +	efuse->dev = dev;
>>>  +
>>>  +	jz4780_efuse_nvmem_config.dev = &pdev->dev;
>>>  +	jz4780_efuse_nvmem_config.priv = efuse;
>>>  +
>>>  +	nvmem = nvmem_register(&jz4780_efuse_nvmem_config);
>> 
>>  devm variant here?
> 
> Good idea! I didn't know that it exists. Allows us to remove
> jz4780_efuse_remove() below.
> 
>> 
>> 
>>>  +	if (IS_ERR(nvmem))
>>>  +		return PTR_ERR(nvmem);
>>>  +
>>>  +	platform_set_drvdata(pdev, nvmem);
>>>  +
>>>  +	return 0;
>>>  +}
>>>  +
>>>  +static int jz4780_efuse_remove(struct platform_device *pdev)
>>>  +{
>>>  +	struct nvmem_device *nvmem = platform_get_drvdata(pdev);
>>>  +
>>>  +	nvmem_unregister(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,
>>>  +	.remove = jz4780_efuse_remove,
>>>  +	.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_DESCRIPTION("Ingenic JZ4780 efuse driver");
>>>  +MODULE_LICENSE("GPL v2");
> 
> BR and thanks,
> Nikolaus Schaller
> 
> 

Re: [RFC v3 1/9] nvmem: add driver for JZ4780 efuse

[Paul Cercueil]

Hi Srinivas,


Le lun., févr. 17, 2020 at 11:36, Srinivas Kandagatla 
<srinivas.kandagatla@linaro.org> a écrit :
> 
> 
> On 16/02/2020 19:20, H. Nikolaus Schaller wrote:
>> 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 | 249 
>> +++++++++++++++++++++++++++++++++++
>>   3 files changed, 261 insertions(+)
>>   create mode 100644 drivers/nvmem/jz4780-efuse.c
>> 
> 
> This patch along with 2/9 should be merged into single patch.
> Also please make sure you run checkpatch.pl before sending!
> 
>> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
>> index 35efab1ba8d9..10f8e08f5e31 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.
>>   \x7f+config JZ4780_EFUSE
>> +	tristate "JZ4780 EFUSE Memory Support"
>> +	depends on MACH_JZ4780 || COMPILE_TEST
> 
> what is that this driver depends on MACH_JZ4780 board?
> 
> 
>> +	depends on HAS_IOMEM
>> +	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..ac03e1900ef9
>> --- /dev/null
>> +++ b/drivers/nvmem/jz4780-efuse.c
>> @@ -0,0 +1,249 @@
>> +// 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>
> ?? why do we need these two headers in this patch
> 
> 
>> +
>> +#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 JZ_EFUSE_START_ADDR		0x200
>> +
>> +#define JZ_EFUSE_EFUCTRL_CS		BIT(30)
>> +#define JZ_EFUSE_EFUCTRL_ADDR_MASK	0x1FF
>> +#define JZ_EFUSE_EFUCTRL_ADDR_SHIFT	21
>> +#define JZ_EFUSE_EFUCTRL_LEN_MASK	0x1F
>> +#define JZ_EFUSE_EFUCTRL_LEN_SHIFT	16
>> +#define JZ_EFUSE_EFUCTRL_PG_EN		BIT(15)
>> +#define JZ_EFUSE_EFUCTRL_WR_EN		BIT(1)
>> +#define JZ_EFUSE_EFUCTRL_RD_EN		BIT(0)
>> +
>> +#define JZ_EFUSE_EFUCFG_INT_EN		BIT(31)
>> +#define JZ_EFUSE_EFUCFG_RD_ADJ_MASK	0xF
> 
> consider using GENMASK for these masks here.
> 
>> +#define JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT	20
>> +#define JZ_EFUSE_EFUCFG_RD_STR_MASK	0xF
>> +#define JZ_EFUSE_EFUCFG_RD_STR_SHIFT	16
>> +#define JZ_EFUSE_EFUCFG_WR_ADJ_MASK	0xF
>> +#define JZ_EFUSE_EFUCFG_WR_ADJ_SHIFT	12
>> +#define JZ_EFUSE_EFUCFG_WR_STR_MASK	0xFFF
>> +#define JZ_EFUSE_EFUCFG_WR_STR_SHIFT	0
>> +
>> +#define JZ_EFUSE_EFUSTATE_WR_DONE	BIT(1)
>> +#define JZ_EFUSE_EFUSTATE_RD_DONE	BIT(0)
>> +
>> +struct jz4780_efuse {
>> +	struct device *dev;
>> +	void __iomem *iomem;
>> +	struct clk *clk;
>> +	unsigned int rd_adj;
>> +	unsigned int rd_strobe;
>> +};
>> +
>> +/* We read 32 byte chunks to avoid complexity in the driver. */
>> +static int jz4780_efuse_read_32bytes(struct jz4780_efuse *efuse, 
>> char *buf,
>> +		unsigned int addr)
>> +{
>> +	unsigned int tmp = 0;
>> +	int i = 0;
> 
> unnecessary initialization of both variables.
> 
>> +	int timeout = 1000;
>> +	int size = 32;
> 
> better to #define this STRIDE/CHUNK size. this driver seems to use 
> this value in multiple places.
> 
>> +
>> +	/* 1. Set config register */
>> +	tmp = readl(efuse->iomem + JZ_EFUCFG);
>> +	tmp &= ~((JZ_EFUSE_EFUCFG_RD_ADJ_MASK << 
>> JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
>> +	| (JZ_EFUSE_EFUCFG_RD_STR_MASK << JZ_EFUSE_EFUCFG_RD_STR_SHIFT));
>> +	tmp |= (efuse->rd_adj << JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
>> +	| (efuse->rd_strobe << JZ_EFUSE_EFUCFG_RD_STR_SHIFT);
> 
> very odd indenting.
> 
>> +	writel(tmp, efuse->iomem + JZ_EFUCFG);
>> +
>> +	/*
>> +	 * 2. Set control register to indicate what to read data address,
>> +	 * read data numbers and read enable.
>> +	 */
>> +	tmp = readl(efuse->iomem + JZ_EFUCTRL);
>> +	tmp &= ~(JZ_EFUSE_EFUCFG_RD_STR_SHIFT
>> +		| (JZ_EFUSE_EFUCTRL_ADDR_MASK << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
>> +		| JZ_EFUSE_EFUCTRL_PG_EN | JZ_EFUSE_EFUCTRL_WR_EN
>> +		| JZ_EFUSE_EFUCTRL_WR_EN);
>> +
>> +	/* Need to select CS bit if address accesses upper 4Kbits memory */
>> +	if (addr >= (JZ_EFUSE_START_ADDR + 512))
>> +		tmp |= JZ_EFUSE_EFUCTRL_CS;
>> +
>> +	tmp |= (addr << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
>> +		| ((size - 1) << JZ_EFUSE_EFUCTRL_LEN_SHIFT)
>> +		| JZ_EFUSE_EFUCTRL_RD_EN;
>> +	writel(tmp, efuse->iomem + JZ_EFUCTRL);
>> +
>> +	/*
>> +	 * 3. Wait status register RD_DONE set to 1 or EFUSE interrupted,
>> +	 * software can read EFUSE data buffer 0 - 8 registers.
>> +	 */
>> +	do {
>> +		tmp = readl(efuse->iomem + JZ_EFUSTATE);
>> +		usleep_range(1000, 2000);
>> +		if (timeout--)
>> +			break;
>> +	} while (!(tmp & JZ_EFUSE_EFUSTATE_RD_DONE));
>> +
>> +	if (timeout <= 0) {
>> +		dev_err(efuse->dev, "Timed out while reading\n");
>> +		return -EAGAIN;
>> +	}
>> +
>> +	for (i = 0; i < (size / 4); i++)
>> +		*((unsigned int *)(buf + i * 4))
> 
> make "unsigned int *buf32" a local variable and use it here, makes it 
> much readable code.
> 
>> +			 = readl(efuse->iomem + JZ_EFUDATA(i));
>> +
>> +	return 0;
>> +}
>> +
>> +/* 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;
>> +
>> +	while (bytes > 0) {
>> +		unsigned int start = offset & ~(32 - 1);
>> +		unsigned chunk = min(bytes, (start + 32 - offset));
>> +
>> +		if (start == offset && chunk == 32) {
>> +			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);
>> +		}
>> +
>> +		val += chunk;
>> +		offset += chunk;
>> +		bytes -= chunk;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static struct nvmem_config jz4780_efuse_nvmem_config = {
>> +	.name = "jz4780-efuse",
>> +	.read_only = true,
> 
> this value comes from device tree bindings, do we still need  to 
> specify this here?

I think its semantic is different - devicetree specifies that you want 
the nvmem to be readonly, this one specifies that the driver cannot do 
read-write anyway.

With that said, there is no .reg_write, so .read_only will be enforced 
to 'true' anyway, so it can be removed.

-Paul

> 
>> +	.size = 1024,
>> +	.word_size = 1,
>> +	.stride = 1,
>> +	.owner = THIS_MODULE,
>> +	.reg_read = jz4780_efuse_read,
>> +};
>> +
>> +static int jz4780_efuse_probe(struct platform_device *pdev)
>> +{
>> +	struct nvmem_device *nvmem;
>> +	struct jz4780_efuse *efuse;
>> +	struct resource *res;
>> +	unsigned long clk_rate;
>> +	struct device *dev = &pdev->dev;
>> +
>> +	efuse = devm_kzalloc(&pdev->dev, sizeof(*efuse), GFP_KERNEL);
>> +	if (!efuse)
>> +		return -ENOMEM;
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	efuse->iomem = devm_ioremap(&pdev->dev, res->start, 
>> resource_size(res));
>> +	if (IS_ERR(efuse->iomem))
>> +		return PTR_ERR(efuse->iomem);
>> +
>> +	efuse->clk = devm_clk_get(&pdev->dev, "bus_clk");
>> +	if (IS_ERR(efuse->clk))
>> +		return PTR_ERR(efuse->clk);
> 
> Who is enabling this clk?
> 
> 
>> +
>> +	clk_rate = clk_get_rate(efuse->clk);
>> +	/*
>> +	 * 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;
>> +	efuse->rd_strobe = ((((35000 * (clk_rate / 1000000)) / 1000000) + 
>> 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;
>> +	}
>> +	efuse->dev = dev;
>> +
>> +	jz4780_efuse_nvmem_config.dev = &pdev->dev;
>> +	jz4780_efuse_nvmem_config.priv = efuse;
>> +
>> +	nvmem = nvmem_register(&jz4780_efuse_nvmem_config);
> 
> devm variant here?
> 
> 
>> +	if (IS_ERR(nvmem))
>> +		return PTR_ERR(nvmem);
>> +
>> +	platform_set_drvdata(pdev, nvmem);
>> +
>> +	return 0;
>> +}
>> +
>> +static int jz4780_efuse_remove(struct platform_device *pdev)
>> +{
>> +	struct nvmem_device *nvmem = platform_get_drvdata(pdev);
>> +
>> +	nvmem_unregister(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,
>> +	.remove = jz4780_efuse_remove,
>> +	.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_DESCRIPTION("Ingenic JZ4780 efuse driver");
>> +MODULE_LICENSE("GPL v2");
>>