Re: [PATCH] Add Ingenic JZ4780 hardware RNG driver

[PrasannaKumar Muralidharan]

On 17 August 2016 at 21:31, Daniel Thompson <daniel.thompson@xxxxxxxxxx> wrote:
> 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 .

Sure, Will submit it as a separate patch.

>> 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).

Will follow the convention.

>> 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?

I missed it. Will take into account while sending next revision.

>>  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.

Will arrange both alphabetically. They will be in sync then.

>>  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.

Missed it. Will fix the issue.

>> +       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).

True. I will change 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");
>>
>

Thanks for the review, appreciate your time.