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

David Mosberger-Tang
2016-05-16T20:17:10Z

Signed-off-by: David Mosberger <davidm@egauge.net>
---
.../devicetree/bindings/nvmem/atmel-secumod.txt | 46 ++++++++
drivers/nvmem/atmel-secumod.c | 125 +++++++++++++++++++++
2 files changed, 171 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..85db709
--- /dev/null
+++ b/Documentation/devicetree/bindings/nvmem/atmel-secumod.txt
@@ -0,0 +1,46 @@
+= 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 registers location and length of the RAM, 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>;
+ status = "okay";
+
+ #address-cells = <1>;
+ #size-cells = <1>;
+
+ secram_auto_erasable at 0000 {
+ 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/atmel-secumod.c b/drivers/nvmem/atmel-secumod.c
new file mode 100644
index 0000000..fda83c9
--- /dev/null
+++ b/drivers/nvmem/atmel-secumod.c
@@ -0,0 +1,125 @@
+/*
+ * 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>
+#include <linux/regmap.h>
+
+static struct regmap_config secumod_regmap_config = {
+ .reg_bits = 32,
+ .val_bits = 32,
+ .reg_stride = 4
+};
+
+static struct nvmem_config econfig = {
+ .name = "secumod",
+ .owner = THIS_MODULE,
+};
+
+/*
+ * 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;
+ struct regmap *regmap;
+ 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);
+
+ secumod_regmap_config.max_register = resource_size(res) - 1;
+
+ regmap = devm_regmap_init_mmio(dev, base, &secumod_regmap_config);
+ if (IS_ERR(regmap)) {
+ dev_err(dev, "%s: regmap init failed\n", __func__);
+ return PTR_ERR(regmap);
+ }
+ econfig.dev = dev;
+ 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