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Subject[PATCH 2/4] nvmem: Add Spreadtrum SC27XX efuse support
Date
From: Freeman Liu <freeman.liu@spreadtrum.com>

This patch add the efuse driver which is embeded in Spreadtrum SC27XX
series PMICs. The sc27xx efuse contains 32 blocks and each block's
data width is 16 bits.

Signed-off-by: Freeman Liu <freeman.liu@spreadtrum.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
---
drivers/nvmem/Kconfig | 11 ++
drivers/nvmem/Makefile | 3 +-
drivers/nvmem/sc27xx-efuse.c | 264 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 277 insertions(+), 1 deletion(-)
create mode 100644 drivers/nvmem/sc27xx-efuse.c

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 54a3c298247b..0a7a470ee859 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -181,4 +181,15 @@ config RAVE_SP_EEPROM
help
Say y here to enable Rave SP EEPROM support.

+config SC27XX_EFUSE
+ tristate "Spreadtrum SC27XX eFuse Support"
+ depends on MFD_SC27XX_PMIC || COMPILE_TEST
+ depends on HAS_IOMEM
+ help
+ This is a simple driver to dump specified values of Spreadtrum
+ SC27XX PMICs from eFuse.
+
+ This driver can also be built as a module. If so, the module
+ will be called nvmem-sc27xx-efuse.
+
endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 27e96a8efd1c..4e8c61628f1a 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -39,4 +39,5 @@ obj-$(CONFIG_NVMEM_SNVS_LPGPR) += nvmem_snvs_lpgpr.o
nvmem_snvs_lpgpr-y := snvs_lpgpr.o
obj-$(CONFIG_RAVE_SP_EEPROM) += nvmem-rave-sp-eeprom.o
nvmem-rave-sp-eeprom-y := rave-sp-eeprom.o
-
+obj-$(CONFIG_SC27XX_EFUSE) += nvmem-sc27xx-efuse.o
+nvmem-sc27xx-efuse-y := sc27xx-efuse.o
diff --git a/drivers/nvmem/sc27xx-efuse.c b/drivers/nvmem/sc27xx-efuse.c
new file mode 100644
index 000000000000..33185d8d82cf
--- /dev/null
+++ b/drivers/nvmem/sc27xx-efuse.c
@@ -0,0 +1,264 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Spreadtrum Communications Inc.
+
+#include <linux/hwspinlock.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/nvmem-provider.h>
+
+/* PMIC global registers definition */
+#define SC27XX_MODULE_EN 0xc08
+#define SC27XX_EFUSE_EN BIT(6)
+
+/* Efuse controller registers definition */
+#define SC27XX_EFUSE_GLB_CTRL 0x0
+#define SC27XX_EFUSE_DATA_RD 0x4
+#define SC27XX_EFUSE_DATA_WR 0x8
+#define SC27XX_EFUSE_BLOCK_INDEX 0xc
+#define SC27XX_EFUSE_MODE_CTRL 0x10
+#define SC27XX_EFUSE_STATUS 0x14
+#define SC27XX_EFUSE_WR_TIMING_CTRL 0x20
+#define SC27XX_EFUSE_RD_TIMING_CTRL 0x24
+#define SC27XX_EFUSE_EFUSE_DEB_CTRL 0x28
+
+/* Mask definition for SC27XX_EFUSE_BLOCK_INDEX register */
+#define SC27XX_EFUSE_BLOCK_MASK GENMASK(4, 0)
+
+/* Bits definitions for SC27XX_EFUSE_MODE_CTRL register */
+#define SC27XX_EFUSE_PG_START BIT(0)
+#define SC27XX_EFUSE_RD_START BIT(1)
+#define SC27XX_EFUSE_CLR_RDDONE BIT(2)
+
+/* Bits definitions for SC27XX_EFUSE_STATUS register */
+#define SC27XX_EFUSE_PGM_BUSY BIT(0)
+#define SC27XX_EFUSE_READ_BUSY BIT(1)
+#define SC27XX_EFUSE_STANDBY BIT(2)
+#define SC27XX_EFUSE_GLOBAL_PROT BIT(3)
+#define SC27XX_EFUSE_RD_DONE BIT(4)
+
+/* Block number and block width (bytes) definitions */
+#define SC27XX_EFUSE_BLOCK_MAX 32
+#define SC27XX_EFUSE_BLOCK_WIDTH 2
+
+/* Timeout (ms) for the trylock of hardware spinlocks */
+#define SC27XX_EFUSE_HWLOCK_TIMEOUT 5000
+
+/* Timeout (us) of polling the status */
+#define SC27XX_EFUSE_POLL_TIMEOUT 3000000
+#define SC27XX_EFUSE_POLL_DELAY_US 10000
+
+struct sc27xx_efuse {
+ struct device *dev;
+ struct regmap *regmap;
+ struct hwspinlock *hwlock;
+ struct mutex mutex;
+ u32 base;
+};
+
+/*
+ * On Spreadtrum platform, we have multi-subsystems will access the unique
+ * efuse controller, so we need one hardware spinlock to synchronize between
+ * the multiple subsystems.
+ */
+static int sc27xx_efuse_lock(struct sc27xx_efuse *efuse)
+{
+ int ret;
+
+ mutex_lock(&efuse->mutex);
+
+ ret = hwspin_lock_timeout_raw(efuse->hwlock,
+ SC27XX_EFUSE_HWLOCK_TIMEOUT);
+ if (ret) {
+ dev_err(efuse->dev, "timeout to get the hwspinlock\n");
+ mutex_unlock(&efuse->mutex);
+ return ret;
+ }
+
+ return 0;
+}
+
+static void sc27xx_efuse_unlock(struct sc27xx_efuse *efuse)
+{
+ hwspin_unlock_raw(efuse->hwlock);
+ mutex_unlock(&efuse->mutex);
+}
+
+static int sc27xx_efuse_poll_status(struct sc27xx_efuse *efuse, u32 bits)
+{
+ int ret;
+ u32 val;
+
+ ret = regmap_read_poll_timeout(efuse->regmap,
+ efuse->base + SC27XX_EFUSE_STATUS,
+ val, (val & bits),
+ SC27XX_EFUSE_POLL_DELAY_US,
+ SC27XX_EFUSE_POLL_TIMEOUT);
+ if (ret) {
+ dev_err(efuse->dev, "timeout to update the efuse status\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static int sc27xx_efuse_read(void *context, u32 offset, void *val, size_t bytes)
+{
+ struct sc27xx_efuse *efuse = context;
+ u32 buf;
+ int ret;
+
+ if (offset > SC27XX_EFUSE_BLOCK_MAX || bytes > SC27XX_EFUSE_BLOCK_WIDTH)
+ return -EINVAL;
+
+ ret = sc27xx_efuse_lock(efuse);
+ if (ret)
+ return ret;
+
+ /* Enable the efuse controller. */
+ ret = regmap_update_bits(efuse->regmap, SC27XX_MODULE_EN,
+ SC27XX_EFUSE_EN, SC27XX_EFUSE_EN);
+ if (ret)
+ goto unlock_efuse;
+
+ /*
+ * Before reading, we should ensure the efuse controller is in
+ * standby state.
+ */
+ ret = sc27xx_efuse_poll_status(efuse, SC27XX_EFUSE_STANDBY);
+ if (ret)
+ goto disable_efuse;
+
+ /* Set the block address to be read. */
+ ret = regmap_write(efuse->regmap,
+ efuse->base + SC27XX_EFUSE_BLOCK_INDEX,
+ offset & SC27XX_EFUSE_BLOCK_MASK);
+ if (ret)
+ goto disable_efuse;
+
+ /* Start reading process from efuse memory. */
+ ret = regmap_update_bits(efuse->regmap,
+ efuse->base + SC27XX_EFUSE_MODE_CTRL,
+ SC27XX_EFUSE_RD_START,
+ SC27XX_EFUSE_RD_START);
+ if (ret)
+ goto disable_efuse;
+
+ /*
+ * Polling the read done status to make sure the reading process
+ * is completed, that means the data can be read out now.
+ */
+ ret = sc27xx_efuse_poll_status(efuse, SC27XX_EFUSE_RD_DONE);
+ if (ret)
+ goto disable_efuse;
+
+ /* Read data from efuse memory. */
+ ret = regmap_read(efuse->regmap, efuse->base + SC27XX_EFUSE_DATA_RD,
+ &buf);
+ if (ret)
+ goto disable_efuse;
+
+ /* Clear the read done flag. */
+ ret = regmap_update_bits(efuse->regmap,
+ efuse->base + SC27XX_EFUSE_MODE_CTRL,
+ SC27XX_EFUSE_CLR_RDDONE,
+ SC27XX_EFUSE_CLR_RDDONE);
+
+disable_efuse:
+ /* Disable the efuse controller after reading. */
+ regmap_update_bits(efuse->regmap, SC27XX_MODULE_EN, SC27XX_EFUSE_EN, 0);
+unlock_efuse:
+ sc27xx_efuse_unlock(efuse);
+
+ if (!ret)
+ memcpy(val, &buf, bytes);
+
+ return ret;
+}
+
+static int sc27xx_efuse_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct nvmem_config econfig = { };
+ struct nvmem_device *nvmem;
+ struct sc27xx_efuse *efuse;
+ int ret;
+
+ efuse = devm_kzalloc(&pdev->dev, sizeof(*efuse), GFP_KERNEL);
+ if (!efuse)
+ return -ENOMEM;
+
+ efuse->regmap = dev_get_regmap(pdev->dev.parent, NULL);
+ if (!efuse->regmap) {
+ dev_err(&pdev->dev, "failed to get efuse regmap\n");
+ return -ENODEV;
+ }
+
+ ret = of_property_read_u32(np, "reg", &efuse->base);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to get efuse base address\n");
+ return ret;
+ }
+
+ ret = of_hwspin_lock_get_id(np, 0);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to get hwspinlock id\n");
+ return ret;
+ }
+
+ efuse->hwlock = hwspin_lock_request_specific(ret);
+ if (!efuse->hwlock) {
+ dev_err(&pdev->dev, "failed to request hwspinlock\n");
+ return -ENXIO;
+ }
+
+ mutex_init(&efuse->mutex);
+ efuse->dev = &pdev->dev;
+ platform_set_drvdata(pdev, efuse);
+
+ econfig.stride = 1;
+ econfig.word_size = 1;
+ econfig.read_only = true;
+ econfig.name = "sc27xx-efuse";
+ econfig.size = SC27XX_EFUSE_BLOCK_MAX * SC27XX_EFUSE_BLOCK_WIDTH;
+ econfig.reg_read = sc27xx_efuse_read;
+ econfig.priv = efuse;
+ econfig.dev = &pdev->dev;
+ nvmem = devm_nvmem_register(&pdev->dev, &econfig);
+ if (IS_ERR(nvmem)) {
+ dev_err(&pdev->dev, "failed to register nvmem config\n");
+ hwspin_lock_free(efuse->hwlock);
+ return PTR_ERR(nvmem);
+ }
+
+ return 0;
+}
+
+static int sc27xx_efuse_remove(struct platform_device *pdev)
+{
+ struct sc27xx_efuse *efuse = platform_get_drvdata(pdev);
+
+ hwspin_lock_free(efuse->hwlock);
+ return 0;
+}
+
+static const struct of_device_id sc27xx_efuse_of_match[] = {
+ { .compatible = "sprd,sc2731-efuse" },
+ { }
+};
+
+static struct platform_driver sc27xx_efuse_driver = {
+ .probe = sc27xx_efuse_probe,
+ .remove = sc27xx_efuse_remove,
+ .driver = {
+ .name = "sc27xx-efuse",
+ .of_match_table = sc27xx_efuse_of_match,
+ },
+};
+
+module_platform_driver(sc27xx_efuse_driver);
+
+MODULE_AUTHOR("Freeman Liu <freeman.liu@spreadtrum.com>");
+MODULE_DESCRIPTION("Spreadtrum SC27xx efuse driver");
+MODULE_LICENSE("GPL v2");
--
2.16.2
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