nvmem: sunxi: Move the SID driver to the nvmem framework

Now that we have the nvmem framework, we can consolidate the common
driver code. Move the driver to the framework, and hopefully, it will
fix the sysfs file creation race.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
[srinivas.kandagatla: Moved to regmap based EEPROM framework]
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Tested-by: Philipp Zabel <p.zabel@pengutronix.de>
Tested-by: Rajendra Nayak <rnayak@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 184 insertions, 0 deletions

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index fa85805bbdb7..8db297821f78 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -25,4 +25,15 @@ config QCOM_QFPROM
 	  This driver can also be built as a module. If so, the module
 	  will be called nvmem_qfprom.
 
+config NVMEM_SUNXI_SID
+	tristate "Allwinner SoCs SID support"
+	depends on ARCH_SUNXI
+	select REGMAP_MMIO
+	help
+	  This is a driver for the 'security ID' available on various Allwinner
+	  devices.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called nvmem_sunxi_sid.
+
 endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index ff44fe99c7d2..4328b930ad9a 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -8,3 +8,5 @@ nvmem_core-y			:= core.o
 # Devices
 obj-$(CONFIG_QCOM_QFPROM)	+= nvmem_qfprom.o
 nvmem_qfprom-y			:= qfprom.o
+obj-$(CONFIG_NVMEM_SUNXI_SID)	+= nvmem_sunxi_sid.o
+nvmem_sunxi_sid-y		:= sunxi_sid.o
diff --git a/drivers/nvmem/sunxi_sid.c b/drivers/nvmem/sunxi_sid.c
new file mode 100644
index 000000000000..14777dd5212d
--- /dev/null
+++ b/drivers/nvmem/sunxi_sid.c
@@ -0,0 +1,171 @@
+/*
+ * Allwinner sunXi SoCs Security ID support.
+ *
+ * Copyright (c) 2013 Oliver Schinagl <oliver@schinagl.nl>
+ * Copyright (C) 2014 Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+
+#include <linux/device.h>
+#include <linux/io.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/slab.h>
+#include <linux/random.h>
+
+
+static struct nvmem_config econfig = {
+	.name = "sunxi-sid",
+	.read_only = true,
+	.owner = THIS_MODULE,
+};
+
+struct sunxi_sid {
+	void __iomem		*base;
+};
+
+/* We read the entire key, due to a 32 bit read alignment requirement. Since we
+ * want to return the requested byte, this results in somewhat slower code and
+ * uses 4 times more reads as needed but keeps code simpler. Since the SID is
+ * only very rarely probed, this is not really an issue.
+ */
+static u8 sunxi_sid_read_byte(const struct sunxi_sid *sid,
+			      const unsigned int offset)
+{
+	u32 sid_key;
+
+	sid_key = ioread32be(sid->base + round_down(offset, 4));
+	sid_key >>= (offset % 4) * 8;
+
+	return sid_key; /* Only return the last byte */
+}
+
+static int sunxi_sid_read(void *context,
+			    const void *reg, size_t reg_size,
+			    void *val, size_t val_size)
+{
+	struct sunxi_sid *sid = context;
+	unsigned int offset = *(u32 *)reg;
+	u8 *buf = val;
+
+	while (val_size) {
+		*buf++ = sunxi_sid_read_byte(sid, offset);
+		val_size--;
+		offset++;
+	}
+
+	return 0;
+}
+
+static int sunxi_sid_write(void *context, const void *data, size_t count)
+{
+	/* Unimplemented, dummy to keep regmap core happy */
+	return 0;
+}
+
+static struct regmap_bus sunxi_sid_bus = {
+	.read = sunxi_sid_read,
+	.write = sunxi_sid_write,
+	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
+	.val_format_endian_default = REGMAP_ENDIAN_NATIVE,
+};
+
+static bool sunxi_sid_writeable_reg(struct device *dev, unsigned int reg)
+{
+	return false;
+}
+
+static struct regmap_config sunxi_sid_regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 8,
+	.reg_stride = 1,
+	.writeable_reg = sunxi_sid_writeable_reg,
+};
+
+static int sunxi_sid_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	struct nvmem_device *nvmem;
+	struct regmap *regmap;
+	struct sunxi_sid *sid;
+	int i, size;
+	char *randomness;
+
+	sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL);
+	if (!sid)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	sid->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(sid->base))
+		return PTR_ERR(sid->base);
+
+	size = resource_size(res) - 1;
+	sunxi_sid_regmap_config.max_register = size;
+
+	regmap = devm_regmap_init(dev, &sunxi_sid_bus, sid,
+				  &sunxi_sid_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(dev, "regmap init failed\n");
+		return PTR_ERR(regmap);
+	}
+
+	econfig.dev = dev;
+	nvmem = nvmem_register(&econfig);
+	if (IS_ERR(nvmem))
+		return PTR_ERR(nvmem);
+
+	randomness = kzalloc(sizeof(u8) * size, GFP_KERNEL);
+	for (i = 0; i < size; i++)
+		randomness[i] = sunxi_sid_read_byte(sid, i);
+
+	add_device_randomness(randomness, size);
+	kfree(randomness);
+
+	platform_set_drvdata(pdev, nvmem);
+
+	return 0;
+}
+
+static int sunxi_sid_remove(struct platform_device *pdev)
+{
+	struct nvmem_device *nvmem = platform_get_drvdata(pdev);
+
+	return nvmem_unregister(nvmem);
+}
+
+static const struct of_device_id sunxi_sid_of_match[] = {
+	{ .compatible = "allwinner,sun4i-a10-sid" },
+	{ .compatible = "allwinner,sun7i-a20-sid" },
+	{/* sentinel */},
+};
+MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);
+
+static struct platform_driver sunxi_sid_driver = {
+	.probe = sunxi_sid_probe,
+	.remove = sunxi_sid_remove,
+	.driver = {
+		.name = "eeprom-sunxi-sid",
+		.of_match_table = sunxi_sid_of_match,
+	},
+};
+module_platform_driver(sunxi_sid_driver);
+
+MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
+MODULE_DESCRIPTION("Allwinner sunxi security id driver");
+MODULE_LICENSE("GPL");