[PATCH] drivers: nvmem: atmel-secumod: New driver for Atmel Secumod nvram

David Mosberger-Tang
2016-05-18T21:06:04Z

Signed-off-by: David Mosberger <davidm@egauge.net>
---
.../devicetree/bindings/nvmem/atmel-secumod.txt | 47 +++++++
drivers/nvmem/Kconfig | 7 +
drivers/nvmem/Makefile | 2 +
drivers/nvmem/atmel-secumod.c | 143 +++++++++++++++++++++
4 files changed, 199 insertions(+)
create mode 100644 Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
create mode 100644 drivers/nvmem/atmel-secumod.c

diff --git a/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt b/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
new file mode 100644
index 0000000..d65cad5
--- /dev/null
+++ b/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
@@ -0,0 +1,47 @@
+= Atmel Secumod device tree bindings =
+
+This binding is intended to represent Atmel's Secumod which is found
+in SAMA5D2 and perhaps others.
+
+Required properties:
+- compatible: should be "atmel,sama5d2-secumod"
+- reg: Should contain RAM location and length, followed
+ by register location and length of the Secumod controller.
+
+= Data cells =
+Are child nodes of secumod, bindings of which as described in
+bindings/nvmem/nvmem.txt
+
+Example:
+
+ secumod at fc040000 {
+ compatible = "atmel,sama5d2-secumod";
+ reg = <0xf8044000 0x1420>, <0xfc040000 0x4000>;
+ reg-names = "SECURAM", "SECUMOD";
+ status = "okay";
+
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges;
+
+ secram-auto-erasable at 0 {
+ reg = <0x0000 0x1000>;
+ };
+ secram at 1000 {
+ reg = <0x1000 0x400>;
+ };
+ ram at 1400 {
+ reg = <0x1400 0x20>;
+ };
+ };
+
+= Data consumers =
+Are device nodes which consume nvmem data cells.
+
+For example:
+
+ ram {
+ ...
+ nvmem-cells = <&ram>;
+ nvmem-cell-names = "RAM";
+ };
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 3041d48..88b21e3 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -101,4 +101,11 @@ config NVMEM_VF610_OCOTP
This driver can also be build as a module. If so, the module will
be called nvmem-vf610-ocotp.

+config NVMEM_ATMEL_SECUMOD
+ tristate "Atmel Secure Module driver"
+ depends on ARCH_AT91
+ help
+ Select this to get support for the secure module (SECUMOD) built
+ into the SAMA5D2 chips.
+
endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 45ab1ae..9cbd950 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -22,3 +22,5 @@ obj-$(CONFIG_NVMEM_SUNXI_SID) += nvmem_sunxi_sid.o
nvmem_sunxi_sid-y := sunxi_sid.o
obj-$(CONFIG_NVMEM_VF610_OCOTP) += nvmem-vf610-ocotp.o
nvmem-vf610-ocotp-y := vf610-ocotp.o
+obj-$(CONFIG_NVMEM_ATMEL_SECUMOD) += nvmem-atmel-secumod.o
+nvmem-atmel-secumod-y := atmel-secumod.o
diff --git a/drivers/nvmem/atmel-secumod.c b/drivers/nvmem/atmel-secumod.c
new file mode 100644
index 0000000..fc5a96b
--- /dev/null
+++ b/drivers/nvmem/atmel-secumod.c
@@ -0,0 +1,143 @@
+/*
+ * Driver for SAMA5D2 secure module (SECUMOD).
+ *
+ * Copyright (C) 2016 eGauge Systems LLC
+ *
+ * David Mosberger <davidm@egauge.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+static int
+secumod_reg_read(void *context, unsigned int reg, void *_val, size_t bytes)
+{
+ void __iomem *base = context;
+ u32 *val = _val;
+ int i = 0, words = bytes / 4;
+
+ while (words--)
+ *val++ = readl(base + reg + (i++ * 4));
+
+ return 0;
+}
+
+static int
+secumod_reg_write(void *context, unsigned int reg, void *_val, size_t bytes)
+{
+ void __iomem *base = context;
+ u32 *val = _val;
+ int i = 0, words = bytes / 4;
+
+ while (words--)
+ writel(*val++, base + reg + (i++ * 4));
+
+ return 0;
+}
+
+static struct nvmem_config econfig = {
+ .name = "secumod",
+ .owner = THIS_MODULE,
+ .stride = 4,
+ .word_size = 1,
+ .reg_read = secumod_reg_read,
+ .reg_write = secumod_reg_write,
+};
+
+/*
+ * Security-module register definitions:
+ */
+#define SECUMOD_RAMRDY 0x0014
+
+/*
+ * Since the secure module may need to automatically erase some of the
+ * RAM, it may take a while for it to be ready. As far as I know,
+ * it's not documented how long this might take in the worst-case.
+ */
+static void
+secumod_wait_ready (void *regs)
+{
+ unsigned long start, stop;
+
+ start = jiffies;
+ while (!(readl(regs + SECUMOD_RAMRDY) & 1))
+ msleep_interruptible(1);
+ stop = jiffies;
+ if (stop != start)
+ pr_info("nvmem-atmel-secumod: it took %u msec for SECUMOD "
+ "to become ready...\n", jiffies_to_msecs(stop - start));
+ else
+ pr_info("nvmem-atmel-secumod: ready\n");
+}
+
+static int secumod_remove(struct platform_device *pdev)
+{
+ struct nvmem_device *nvmem = platform_get_drvdata(pdev);
+
+ return nvmem_unregister(nvmem);
+}
+
+static int secumod_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct resource *res;
+ struct nvmem_device *nvmem;
+ void __iomem *base;
+
+ /*
+ * Map controller address temporarily so we can ensure that
+ * the hardware is ready:
+ */
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+ base = devm_ioremap_resource(dev, res);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ secumod_wait_ready(base);
+ devm_iounmap(dev, base);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ base = devm_ioremap_resource(dev, res);
+
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ econfig.size = resource_size(res);
+ econfig.dev = dev;
+ econfig.priv = base;
+
+ nvmem = nvmem_register(&econfig);
+ if (IS_ERR(nvmem))
+ return PTR_ERR(nvmem);
+
+ platform_set_drvdata(pdev, nvmem);
+
+ return 0;
+}
+
+static const struct of_device_id secumod_of_match[] = {
+ { .compatible = "atmel,sama5d2-secumod",},
+ {/* sentinel */},
+};
+MODULE_DEVICE_TABLE(of, secumod_of_match);
+
+static struct platform_driver secumod_driver = {
+ .probe = secumod_probe,
+ .remove = secumod_remove,
+ .driver = {
+ .name = "atmel,sama5d2-secumod",
+ .of_match_table = secumod_of_match,
+ },
+};
+module_platform_driver(secumod_driver);
+MODULE_AUTHOR("David Mosberger <davidm@egauge.net>");
+MODULE_DESCRIPTION("Atmel Secumod driver");
+MODULE_LICENSE("GPL v2");
--
1.9.1