[PATCH 2/3] nvmem: Add Sophgo SG2044 eFuse driver

[Inochi Amaoto <inochiama@gmail.com>]

Sophgo SoCs such as SG2044 contain eFuses used to store
factory-programmed data.

As for SG2044, HW automatically loads the eFuse content
into shadow registers which are organized as 32bit values
exposed as MMIO.

Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
---
 drivers/nvmem/Kconfig        |  12 +++
 drivers/nvmem/Makefile       |   2 +
 drivers/nvmem/sophgo-efuse.c | 176 +++++++++++++++++++++++++++++++++++
 3 files changed, 190 insertions(+)
 create mode 100644 drivers/nvmem/sophgo-efuse.c

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index c36c2a4c2a0b..a7936dd65bdd 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -465,6 +465,18 @@ config NVMEM_SNVS_LPGPR
 	  This driver can also be built as a module. If so, the module
 	  will be called nvmem-snvs-lpgpr.
 
+config NVMEM_SOPHGO_EFUSE
+	tristate "Sophgo eFuse support"
+	depends on ARCH_SOPHGO || COMPILE_TEST
+	default ARCH_SOPHGO
+	help
+	  Say y here to enable support for reading eFuses on Sophgo SoCs
+	  such as the CV1800B. These are e.g. used to store factory programmed
+	  calibration data required for the builtin ethernet PHY.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called nvmem-sophgo-efuse.
+
 config NVMEM_SPMI_SDAM
 	tristate "SPMI SDAM Support"
 	depends on SPMI
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 2bbfb9ff1885..430ddddf8c3c 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -79,6 +79,8 @@ obj-$(CONFIG_NVMEM_SC27XX_EFUSE)	+= nvmem-sc27xx-efuse.o
 nvmem-sc27xx-efuse-y			:= sc27xx-efuse.o
 obj-$(CONFIG_NVMEM_SNVS_LPGPR)		+= nvmem_snvs_lpgpr.o
 nvmem_snvs_lpgpr-y			:= snvs_lpgpr.o
+obj-$(CONFIG_NVMEM_SOPHGO_EFUSE)	+= nvmem-sophgo-efuse.o
+nvmem-sophgo-efuse-y			:= sophgo-efuse.o
 obj-$(CONFIG_NVMEM_SPMI_SDAM)		+= nvmem_qcom-spmi-sdam.o
 nvmem_qcom-spmi-sdam-y			+= qcom-spmi-sdam.o
 obj-$(CONFIG_NVMEM_SPRD_EFUSE)		+= nvmem_sprd_efuse.o
diff --git a/drivers/nvmem/sophgo-efuse.c b/drivers/nvmem/sophgo-efuse.c
new file mode 100644
index 000000000000..5f90adaf8e4f
--- /dev/null
+++ b/drivers/nvmem/sophgo-efuse.c
@@ -0,0 +1,176 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Sophgo SoC eFuse driver
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/cleanup.h>
+#include <linux/iopoll.h>
+#include <linux/math.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/nvmem-provider.h>
+#include <linux/platform_device.h>
+
+#define SG2044_EFUSE_CONTENT_SIZE		0x400
+
+#define SG2044_EFUSE_MD				0x000
+#define SG2044_EFUSE_ADR			0x004
+#define SG2044_EFUSE_RD_DATA			0x00c
+
+#define SG2044_EFUSE_MODE			GENMASK(1, 0)
+#define SG2044_EFUSE_MODE_READ			2
+
+#define SG2044_EFUSE_BOOT_DONE			BIT(7)
+#define SG2044_BOOT_TIMEOUT			10000
+
+#define SG2044_EFUSE_ADR_ADDR			GENMASK(7, 0)
+
+#define SG2044_EFUSE_ALIGN			4
+
+struct sophgo_efuses {
+	void __iomem *base;
+	struct clk_bulk_data *clks;
+	int num_clks;
+	struct mutex mutex;
+};
+
+static int sg2044_efuse_wait_mode(struct sophgo_efuses *efuse)
+{
+	u32 value;
+
+	return readl_poll_timeout(efuse->base + SG2044_EFUSE_MD, value,
+				  FIELD_GET(SG2044_EFUSE_MODE, value) == 0,
+				  1, SG2044_BOOT_TIMEOUT);
+}
+
+static int sg2044_efuse_set_mode(struct sophgo_efuses *efuse, int mode)
+{
+	u32 val = readl(efuse->base + SG2044_EFUSE_MD);
+
+	val &= ~SG2044_EFUSE_MODE;
+	val |= FIELD_PREP(SG2044_EFUSE_MODE, mode);
+
+	writel(val, efuse->base + SG2044_EFUSE_MD);
+
+	return sg2044_efuse_wait_mode(efuse);
+}
+
+static u32 sg2044_efuses_read_strip(struct sophgo_efuses *efuse,
+				    unsigned int offset, u32 *strip)
+{
+	u32 val = FIELD_PREP(SG2044_EFUSE_ADR_ADDR, offset);
+	int ret;
+
+	guard(mutex)(&efuse->mutex);
+
+	writel(val, efuse->base + SG2044_EFUSE_ADR);
+
+	ret = sg2044_efuse_set_mode(efuse, SG2044_EFUSE_MODE_READ);
+	if (ret < 0)
+		return ret;
+
+	*strip = readl(efuse->base + SG2044_EFUSE_RD_DATA);
+
+	return 0;
+}
+
+static int sg2044_efuses_read(void *context, unsigned int offset, void *val,
+			      size_t bytes)
+{
+	struct sophgo_efuses *efuse = context;
+	unsigned int start, start_offset, end, i;
+	u32 value;
+	u8 *buf;
+	int ret;
+
+	start = rounddown(offset, SG2044_EFUSE_ALIGN);
+	end = roundup(offset + bytes, SG2044_EFUSE_ALIGN);
+	start_offset = offset - start;
+
+	start /= SG2044_EFUSE_ALIGN;
+	end /= SG2044_EFUSE_ALIGN;
+
+	ret = readl_poll_timeout(efuse->base + SG2044_EFUSE_MD, value,
+				 (value & SG2044_EFUSE_BOOT_DONE),
+				 1, SG2044_BOOT_TIMEOUT);
+	if (ret < 0)
+		return ret;
+
+	buf = kzalloc(end - start, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	for (i = start; i < end; i++) {
+		ret = sg2044_efuses_read_strip(efuse, i, &value);
+		if (ret)
+			goto failed;
+
+		memcpy(&buf[(i - start) * 4], &value, SG2044_EFUSE_ALIGN);
+	}
+
+	memcpy(val, buf + start_offset, bytes);
+
+failed:
+	kfree(buf);
+
+	return ret;
+}
+
+static int sophgo_efuses_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct sophgo_efuses *efuse;
+	struct nvmem_config config = {
+		.dev = &pdev->dev,
+		.add_legacy_fixed_of_cells = true,
+		.read_only = true,
+		.reg_read = sg2044_efuses_read,
+		.stride = 1,
+		.word_size = 1,
+		.name = "sophgo-efuse",
+		.id = NVMEM_DEVID_AUTO,
+		.root_only = true,
+	};
+
+	efuse = devm_kzalloc(dev, sizeof(*efuse), GFP_KERNEL);
+	if (!efuse)
+		return -ENOMEM;
+
+	efuse->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(efuse->base))
+		return PTR_ERR(efuse->base);
+
+	efuse->num_clks = devm_clk_bulk_get_all_enabled(&pdev->dev, &efuse->clks);
+	if (efuse->num_clks < 0)
+		return dev_err_probe(dev, efuse->num_clks, "failed to get clocks\n");
+
+	config.priv = efuse;
+	config.size = SG2044_EFUSE_CONTENT_SIZE;
+
+	return PTR_ERR_OR_ZERO(devm_nvmem_register(config.dev, &config));
+}
+
+static const struct of_device_id sophgo_efuses_of_match[] = {
+	{ .compatible = "sophgo,sg2044-efuse", },
+	{}
+};
+
+MODULE_DEVICE_TABLE(of, sophgo_efuses_of_match);
+
+static struct platform_driver sophgo_efuses_driver = {
+	.driver = {
+		.name = "sophgo_efuse",
+		.of_match_table = sophgo_efuses_of_match,
+	},
+	.probe = sophgo_efuses_probe,
+};
+
+module_platform_driver(sophgo_efuses_driver);
+
+MODULE_AUTHOR("Inochi Amaoto <inochiama@gmail.com>");
+MODULE_DESCRIPTION("Sophgo efuse driver");
+MODULE_LICENSE("GPL");
-- 
2.56.0