Re: [PATCH] Add Ingenic JZ4780 hardware RNG driver

From: Daniel Thompson
Date: Wed Aug 17 2016 - 12:02:11 EST

On 17/08/16 16:35, PrasannaKumar Muralidharan wrote:
This patch adds support for hardware random number generator present in
JZ4780 SoC.

Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@xxxxxxxxx>
---
.../devicetree/bindings/rng/ingenic,jz4780-rng.txt | 12 +++
MAINTAINERS | 5 +
arch/mips/boot/dts/ingenic/jz4780.dtsi | 7 +-
drivers/char/hw_random/Kconfig | 14 +++
drivers/char/hw_random/Makefile | 1 +
drivers/char/hw_random/jz4780-rng.c | 105 +++++++++++++++++++++
6 files changed, 143 insertions(+), 1 deletion(-)
create mode 100644 Documentation/devicetree/bindings/rng/ingenic,jz4780-rng.txt
create mode 100644 drivers/char/hw_random/jz4780-rng.c

diff --git a/Documentation/devicetree/bindings/rng/ingenic,jz4780-rng.txt b/Documentation/devicetree/bindings/rng/ingenic,jz4780-rng.txt
new file mode 100644
index 0000000..03abf56
--- /dev/null
+++ b/Documentation/devicetree/bindings/rng/ingenic,jz4780-rng.txt
@@ -0,0 +1,12 @@
+Ingenic jz4780 RNG driver
+
+Required properties:
+- compatible : Should be "ingenic,jz4780-rng"
+- reg : Specifies base physical address and size of the registers.
+
+Example:
+
+rng: rng@100000D8 {
+ compatible = "ingenic,jz4780-rng";
+ reg = <0x100000D8 0x8>;
+};

Device tree bindings should be a separate patch. See Documentation/devicetree/bindings/submitting-patches.txt .


diff --git a/MAINTAINERS b/MAINTAINERS
index 08e9efe..c0c66eb 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6002,6 +6002,11 @@ M: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@xxxxxxxxxx>
S: Maintained
F: drivers/dma/dma-jz4780.c

+INGENIC JZ4780 HW RNG Driver
+M: PrasannaKumar Muralidharan <prasannatsmkumar@xxxxxxxxx>
+S: Maintained
+F: drivers/char/hw_random/jz4780-rng.c
+
INTEGRITY MEASUREMENT ARCHITECTURE (IMA)
M: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
M: Dmitry Kasatkin <dmitry.kasatkin@xxxxxxxxx>
diff --git a/arch/mips/boot/dts/ingenic/jz4780.dtsi b/arch/mips/boot/dts/ingenic/jz4780.dtsi
index b868b42..f11d139 100644
--- a/arch/mips/boot/dts/ingenic/jz4780.dtsi
+++ b/arch/mips/boot/dts/ingenic/jz4780.dtsi
@@ -36,7 +36,7 @@

cgu: jz4780-cgu@10000000 {
compatible = "ingenic,jz4780-cgu";
- reg = <0x10000000 0x100>;
+ reg = <0x10000000 0xD8>;
clocks = <&ext>, <&rtc>;
clock-names = "ext", "rtc";
@@ -44,6 +44,11 @@
#clock-cells = <1>;
};

+ rng: jz4780-rng@100000D8 {
+ compatible = "ingenic,jz4780-rng";
+ reg = <0x100000D8 0x8>;
+ };
+
uart0: serial@10030000 {
compatible = "ingenic,jz4780-uart";
reg = <0x10030000 0x100>;

Updates to device tree files are also normally sent as a separate patch later in the series than the driver itself (at least they are in arm land).


diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 56ad5a59..c336fe8 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -294,6 +294,20 @@ config HW_RANDOM_POWERNV

If unsure, say Y.

+config HW_RANDOM_JZ4780
+ tristate "JZ4780 HW random number generator support"
+ depends on MACH_INGENIC
+ depends on HAS_IOMEM
+ default HW_RANDOM
+ ---help---
+ This driver provides kernel-side support for the Random Number
+ Generator hardware found on JZ4780 SOCs.
+
+ To compile this driver as a module, choose M here: the
+ module will be called jz4780-rng.
+
+ If unsure, say Y.
+

Shouldn't this be inserted either in alphabetic order (which not applicable for this file) or at the end of the file?


config HW_RANDOM_EXYNOS
tristate "EXYNOS HW random number generator support"
depends on ARCH_EXYNOS || COMPILE_TEST
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 04bb0b0..a155066 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_HW_RANDOM_PSERIES) += pseries-rng.o
obj-$(CONFIG_HW_RANDOM_POWERNV) += powernv-rng.o
obj-$(CONFIG_HW_RANDOM_EXYNOS) += exynos-rng.o
obj-$(CONFIG_HW_RANDOM_HISI) += hisi-rng.o
+obj-$(CONFIG_HW_RANDOM_JZ4780) += jz4780-rng.o

This looks like it inserts into the makefile in a gratuitously different order than the one in the KConfig file.


obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
diff --git a/drivers/char/hw_random/jz4780-rng.c b/drivers/char/hw_random/jz4780-rng.c
new file mode 100644
index 0000000..c9d2cde
--- /dev/null
+++ b/drivers/char/hw_random/jz4780-rng.c
@@ -0,0 +1,105 @@
+/*
+ * jz4780-rng.c - Random Number Generator driver for J4780
+ *
+ * Copyright 2016 (C) PrasannaKumar Muralidharan <prasannatsmkumar@xxxxxxxxx>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/hw_random.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+
+#define REG_RNG_CTRL 0x0
+#define REG_RNG_DATA 0x4
+
+struct jz4780_rng {
+ struct device *dev;
+ struct hwrng rng;
+ void __iomem *mem;
+};
+
+static u32 jz4780_rng_readl(struct jz4780_rng *rng, u32 offset)
+{
+ return readl(rng->mem + offset);
+}
+
+static void jz4780_rng_writel(struct jz4780_rng *rng, u32 val, u32 offset)
+{
+ writel(val, rng->mem + offset);
+}
+
+static int jz4780_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+ struct jz4780_rng *jz4780_rng = container_of(rng, struct jz4780_rng,
+ rng);
+ u32 *data = buf;
+ *data = jz4780_rng_readl(jz4780_rng, REG_RNG_DATA);
+ return 4;
+}
+
+static int jz4780_rng_probe(struct platform_device *pdev)
+{
+ struct jz4780_rng *jz4780_rng;
+ struct resource *res;
+ resource_size_t size;
+ int ret;
+
+ jz4780_rng = devm_kzalloc(&pdev->dev, sizeof(struct jz4780_rng),
+ GFP_KERNEL);
+ if (!jz4780_rng)
+ return -ENOMEM;
+
+ jz4780_rng->dev = &pdev->dev;
+ jz4780_rng->rng.name = "jz4780";
+ jz4780_rng->rng.read = jz4780_rng_read;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

If platform_get_resource() returns NULL I think this code will crash.


+ size = resource_size(res);
+
+ jz4780_rng->mem = devm_ioremap(&pdev->dev, res->start, size);
+ if (IS_ERR(jz4780_rng->mem))
+ return PTR_ERR(jz4780_rng->mem);
+
+ platform_set_drvdata(pdev, jz4780_rng);
+ jz4780_rng_writel(jz4780_rng, 1, REG_RNG_CTRL);
+ ret = hwrng_register(&jz4780_rng->rng);
+ return ret;
+}
+
+static int jz4780_rng_remove(struct platform_device *pdev)
+{
+ struct jz4780_rng *jz4780_rng = platform_get_drvdata(pdev);
+
+ jz4780_rng_writel(jz4780_rng, 0, REG_RNG_CTRL);
+ hwrng_unregister(&jz4780_rng->rng);

These two are in same order as probe() function. I would expect them to be reversed (so hardware cannot be shutdown until we have unregistered it).


+
+ return 0;
+}
+
+static const struct of_device_id jz4780_rng_dt_match[] = {
+ { .compatible = "ingenic,jz4780-rng", },
+ { },
+};
+MODULE_DEVICE_TABLE(of, jz4780_rng_dt_match);
+
+static struct platform_driver jz4780_rng_driver = {
+ .driver = {
+ .name = "jz4780-rng",
+ .of_match_table = jz4780_rng_dt_match,
+ },
+ .probe = jz4780_rng_probe,
+ .remove = jz4780_rng_remove,
+};
+module_platform_driver(jz4780_rng_driver);
+
+MODULE_DESCRIPTION("Ingenic JZ4780 H/W Random Number Generator driver");
+MODULE_AUTHOR("PrasannaKumar Muralidharan <prasannatsmkumar@xxxxxxxxx>");
+MODULE_LICENSE("GPL");