Re: [PATCH v2 5/7] hwrng: st: Add support for ST's HW Random Number Generator
On Mon, 05 Oct 2015, Daniel Thompson wrote:
> On 05/10/15 13:11, Lee Jones wrote:
> >On Mon, 05 Oct 2015, Daniel Thompson wrote:
> >>Late but...
> >
> >That's okay. Fixup patches can always be submitted.
> >
> >We have forever. :)
> >
> >>On 17/09/15 14:45, Lee Jones wrote:
> >>>diff --git a/drivers/char/hw_random/Makefile
> >>>b/drivers/char/hw_random/Makefile
> >>>index 055bb01..8bcfb45 100644
> >>>--- a/drivers/char/hw_random/Makefile
> >>>+++ b/drivers/char/hw_random/Makefile
> >>>@@ -30,4 +30,5 @@ obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
> >>> obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
> >>> obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
> >>> obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
> >>>+obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
> >>> obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
> >>>diff --git a/drivers/char/hw_random/st-rng.c
> >>>b/drivers/char/hw_random/st-rng.c
> >>>new file mode 100644
> >>>index 000..8c8a435
> >>>--- /dev/null
> >>>+++ b/drivers/char/hw_random/st-rng.c
> >>>@@ -0,0 +1,144 @@
> >>>+/*
> >>>+ * ST Random Number Generator Driver ST's Platforms
> >>>+ *
> >>>+ * Author: Pankaj Dev:
> >>>+ * Lee Jones
> >>>+ *
> >>>+ * Copyright (C) 2015 STMicroelectronics (R&D) Limited
> >>>+ *
> >>>+ * 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
> >>>+#include
> >>>+#include
> >>>+#include
> >>>+#include
> >>>+#include
> >>>+#include
> >>>+#include
> >>>+
> >>>+/* Registers */
> >>>+#define ST_RNG_STATUS_REG 0x20
> >>>+#define ST_RNG_DATA_REG 0x24
> >>>+
> >>>+/* Registers fields */
> >>>+#define ST_RNG_STATUS_BAD_SEQUENCEBIT(0)
> >>>+#define ST_RNG_STATUS_BAD_ALTERNANCE BIT(1)
> >>>+#define ST_RNG_STATUS_FIFO_FULL BIT(5)
> >>>+
> >>>+#define ST_RNG_FIFO_SIZE 8
> >>>+#define ST_RNG_SAMPLE_SIZE2 /* 2 Byte (16bit) samples */
> >>>+
> >>>+/* Samples are available every 0.667us, which we round to 1us */
> >>>+#define ST_RNG_FILL_FIFO_TIMEOUT (1 * (ST_RNG_FIFO_SIZE /
> >>>ST_RNG_SAMPLE_SIZE))
> >>>+
> >>>+struct st_rng_data {
> >>>+ void __iomem*base;
> >>>+ struct clk *clk;
> >>>+ struct hwrngops;
> >>>+};
> >>>+
> >>>+static int st_rng_read(struct hwrng *rng, void *data, size_t max, bool
> >>>wait)
> >>>+{
> >>>+ struct st_rng_data *ddata = (struct st_rng_data *)rng->priv;
> >>>+ u32 status;
> >>>+ int i;
> >>>+
> >>>+ if (max < sizeof(u16))
> >>>+ return -EINVAL;
> >>>+
> >>>+ /* Wait until FIFO is full - max 4uS*/
> >>>+ for (i = 0; i < ST_RNG_FILL_FIFO_TIMEOUT; i++) {
> >>>+ status = readl_relaxed(ddata->base + ST_RNG_STATUS_REG);
> >>>+ if (status & ST_RNG_STATUS_FIFO_FULL)
> >>>+ break;
> >>>+ udelay(1);
> >>
> >>How much bandwidth does using udelay() cost? I think it could be
> >>>10% compared to a tighter polling loop.
> >
> >Samples are only available every 0.7uS and we only do this for every
> >4. The maximum it could 'cost' is <1uS. Do we really want to fuss
> >over that tiny amount of time? It's an understandable point if we
> >were talking about milliseconds, but a single microsecond?
>
> This code is called in a tight loop so we're not talking about a
> *single* microsecond! We are are talking about about one microsecond
> in every five[1] and yes, I think we should care about that.
>
> It takes 2.67uS for the FIFO to come ready so with a polling
> interval of 1uS + loop overhead so I would fully expect on average
> to "waste" 0.5uS each time st_rng_read() is called (in a tight
> loop).
>
> [1]... point three recurring ;-)
`time dd if=/dev/hwrng of=/dev/null bs=1 count=10M`
/* Current code, inc delay */
Run 1: real 0m17.996s
Run 2: real 0m17.991s
Run 3: real 0m17.996s
Run 4: real 0m18.000s
Run 5: real 0m18.000s
Total 0m89.983s
/* Tight loop, no delay */
Run 1: real 0m18.011s
Run 2: real 0m17.995s
Run 3: real 0m18.005s
Run 4: real 0m18.020s
Run 5: real 0m17.990s
Total 0m90.021s
(89.983 / 90.021) * 100 = 99.958%
0.042% saving.
Not quite the >10% predicted. I'd say that's negligible.
> >>>+ }
> >>>+
> >>>+ if (i == ST_RNG_FILL_FIFO_TIMEOUT)
> >>>+ return 0;
> >>
> >>Isn't a timeout an error condition?
> >
> >Yes, which is why we're returning 0. In this context 0 == 'no data'.
> >This will be converted to -EAGAIN if the caller did not request
> >NONBLOCKING.
>
> I took the view that hitting the timeout means the hardware is
> broken. Is it likely that the next time we call it there will be
> data ready? If it is should it be trusted?
>From experience gained whilst testing, I can say that when returning
an error the HNG breaks and the user receives an error. If instead we
return 0, we get to have another go and random numbers again pour
out. Perhaps we're just not waiting long
Re: [PATCH v2 5/7] hwrng: st: Add support for ST's HW Random Number Generator
On 05/10/15 13:11, Lee Jones wrote:
On Mon, 05 Oct 2015, Daniel Thompson wrote:
Late but...
That's okay. Fixup patches can always be submitted.
We have forever. :)
On 17/09/15 14:45, Lee Jones wrote:
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 055bb01..8bcfb45 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -30,4 +30,5 @@ obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
+obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
diff --git a/drivers/char/hw_random/st-rng.c b/drivers/char/hw_random/st-rng.c
new file mode 100644
index 000..8c8a435
--- /dev/null
+++ b/drivers/char/hw_random/st-rng.c
@@ -0,0 +1,144 @@
+/*
+ * ST Random Number Generator Driver ST's Platforms
+ *
+ * Author: Pankaj Dev:
+ * Lee Jones
+ *
+ * Copyright (C) 2015 STMicroelectronics (R&D) Limited
+ *
+ * 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
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+
+/* Registers */
+#define ST_RNG_STATUS_REG 0x20
+#define ST_RNG_DATA_REG0x24
+
+/* Registers fields */
+#define ST_RNG_STATUS_BAD_SEQUENCE BIT(0)
+#define ST_RNG_STATUS_BAD_ALTERNANCE BIT(1)
+#define ST_RNG_STATUS_FIFO_FULLBIT(5)
+
+#define ST_RNG_FIFO_SIZE 8
+#define ST_RNG_SAMPLE_SIZE 2 /* 2 Byte (16bit) samples */
+
+/* Samples are available every 0.667us, which we round to 1us */
+#define ST_RNG_FILL_FIFO_TIMEOUT (1 * (ST_RNG_FIFO_SIZE /
ST_RNG_SAMPLE_SIZE))
+
+struct st_rng_data {
+ void __iomem*base;
+ struct clk *clk;
+ struct hwrngops;
+};
+
+static int st_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+ struct st_rng_data *ddata = (struct st_rng_data *)rng->priv;
+ u32 status;
+ int i;
+
+ if (max < sizeof(u16))
+ return -EINVAL;
+
+ /* Wait until FIFO is full - max 4uS*/
+ for (i = 0; i < ST_RNG_FILL_FIFO_TIMEOUT; i++) {
+ status = readl_relaxed(ddata->base + ST_RNG_STATUS_REG);
+ if (status & ST_RNG_STATUS_FIFO_FULL)
+ break;
+ udelay(1);
How much bandwidth does using udelay() cost? I think it could be
10% compared to a tighter polling loop.
Samples are only available every 0.7uS and we only do this for every
4. The maximum it could 'cost' is <1uS. Do we really want to fuss
over that tiny amount of time? It's an understandable point if we
were talking about milliseconds, but a single microsecond?
This code is called in a tight loop so we're not talking about a
*single* microsecond! We are are talking about about one microsecond in
every five[1] and yes, I think we should care about that.
It takes 2.67uS for the FIFO to come ready so with a polling interval of
1uS + loop overhead so I would fully expect on average to "waste" 0.5uS
each time st_rng_read() is called (in a tight loop).
[1]... point three recurring ;-)
+ }
+
+ if (i == ST_RNG_FILL_FIFO_TIMEOUT)
+ return 0;
Isn't a timeout an error condition?
Yes, which is why we're returning 0. In this context 0 == 'no data'.
This will be converted to -EAGAIN if the caller did not request
NONBLOCKING.
I took the view that hitting the timeout means the hardware is broken.
Is it likely that the next time we call it there will be data ready? If
it is should it be trusted?
Daniel.
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Re: [PATCH v2 5/7] hwrng: st: Add support for ST's HW Random Number Generator
On Mon, 05 Oct 2015, Daniel Thompson wrote:
> Late but...
That's okay. Fixup patches can always be submitted.
We have forever. :)
> On 17/09/15 14:45, Lee Jones wrote:
> >diff --git a/drivers/char/hw_random/Makefile
> >b/drivers/char/hw_random/Makefile
> >index 055bb01..8bcfb45 100644
> >--- a/drivers/char/hw_random/Makefile
> >+++ b/drivers/char/hw_random/Makefile
> >@@ -30,4 +30,5 @@ obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
> > obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
> > obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
> > obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
> >+obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
> > obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
> >diff --git a/drivers/char/hw_random/st-rng.c
> >b/drivers/char/hw_random/st-rng.c
> >new file mode 100644
> >index 000..8c8a435
> >--- /dev/null
> >+++ b/drivers/char/hw_random/st-rng.c
> >@@ -0,0 +1,144 @@
> >+/*
> >+ * ST Random Number Generator Driver ST's Platforms
> >+ *
> >+ * Author: Pankaj Dev:
> >+ * Lee Jones
> >+ *
> >+ * Copyright (C) 2015 STMicroelectronics (R&D) Limited
> >+ *
> >+ * 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
> >+#include
> >+#include
> >+#include
> >+#include
> >+#include
> >+#include
> >+#include
> >+
> >+/* Registers */
> >+#define ST_RNG_STATUS_REG 0x20
> >+#define ST_RNG_DATA_REG 0x24
> >+
> >+/* Registers fields */
> >+#define ST_RNG_STATUS_BAD_SEQUENCE BIT(0)
> >+#define ST_RNG_STATUS_BAD_ALTERNANCEBIT(1)
> >+#define ST_RNG_STATUS_FIFO_FULL BIT(5)
> >+
> >+#define ST_RNG_FIFO_SIZE8
> >+#define ST_RNG_SAMPLE_SIZE 2 /* 2 Byte (16bit) samples */
> >+
> >+/* Samples are available every 0.667us, which we round to 1us */
> >+#define ST_RNG_FILL_FIFO_TIMEOUT (1 * (ST_RNG_FIFO_SIZE /
> >ST_RNG_SAMPLE_SIZE))
> >+
> >+struct st_rng_data {
> >+void __iomem*base;
> >+struct clk *clk;
> >+struct hwrngops;
> >+};
> >+
> >+static int st_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
> >+{
> >+struct st_rng_data *ddata = (struct st_rng_data *)rng->priv;
> >+u32 status;
> >+int i;
> >+
> >+if (max < sizeof(u16))
> >+return -EINVAL;
> >+
> >+/* Wait until FIFO is full - max 4uS*/
> >+for (i = 0; i < ST_RNG_FILL_FIFO_TIMEOUT; i++) {
> >+status = readl_relaxed(ddata->base + ST_RNG_STATUS_REG);
> >+if (status & ST_RNG_STATUS_FIFO_FULL)
> >+break;
> >+udelay(1);
>
> How much bandwidth does using udelay() cost? I think it could be
> >10% compared to a tighter polling loop.
Samples are only available every 0.7uS and we only do this for every
4. The maximum it could 'cost' is <1uS. Do we really want to fuss
over that tiny amount of time? It's an understandable point if we
were talking about milliseconds, but a single microsecond?
> >+}
> >+
> >+if (i == ST_RNG_FILL_FIFO_TIMEOUT)
> >+return 0;
>
> Isn't a timeout an error condition?
Yes, which is why we're returning 0. In this context 0 == 'no data'.
This will be converted to -EAGAIN if the caller did not request
NONBLOCKING.
> >+
> >+for (i = 0; i < ST_RNG_FIFO_SIZE && i < max; i += 2)
> >+*(u16 *)(data + i) =
> >+readl_relaxed(ddata->base + ST_RNG_DATA_REG);
> >+
> >+return i; /* No of bytes read */
> >+}
> >+
> >+static int st_rng_probe(struct platform_device *pdev)
> >+{
> >+struct st_rng_data *ddata;
> >+struct resource *res;
> >+struct clk *clk;
> >+void __iomem *base;
> >+int ret;
> >+
> >+ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
> >+if (!ddata)
> >+return -ENOMEM;
> >+
> >+res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >+base = devm_ioremap_resource(&pdev->dev, res);
> >+if (IS_ERR(base))
> >+return PTR_ERR(base);
> >+
> >+clk = devm_clk_get(&pdev->dev, NULL);
> >+if (IS_ERR(clk))
> >+return PTR_ERR(clk);
> >+
> >+ret = clk_prepare_enable(clk);
> >+if (ret)
> >+return ret;
> >+
> >+ddata->ops.priv = (unsigned long)ddata;
> >+ddata->ops.read = st_rng_read;
> >+ddata->ops.name = pdev->name;
> >+ddata->base = base;
> >+ddata->clk = clk;
> >+
> >+dev_set_drvdata(&pdev->dev, ddata);
> >+
> >+ret = hwrng_register(&ddata->ops);
> >+if (ret) {
> >+dev_err(&pdev->dev, "Failed to register HW RNG\n");
>
> Why shout about this particular error but not any others? Perhaps
> just rely on the driver core to report the error here?
I have omitted error prints from subsystem calls which do all the
shouting required. Unfortunately the HWRNG is somewhat stuck in the
past in a number of ways; a lack of subsystem level sh
Re: [PATCH v2 5/7] hwrng: st: Add support for ST's HW Random Number Generator
Hi Lee
Late but...
On 17/09/15 14:45, Lee Jones wrote:
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 055bb01..8bcfb45 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -30,4 +30,5 @@ obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
+obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
diff --git a/drivers/char/hw_random/st-rng.c b/drivers/char/hw_random/st-rng.c
new file mode 100644
index 000..8c8a435
--- /dev/null
+++ b/drivers/char/hw_random/st-rng.c
@@ -0,0 +1,144 @@
+/*
+ * ST Random Number Generator Driver ST's Platforms
+ *
+ * Author: Pankaj Dev:
+ * Lee Jones
+ *
+ * Copyright (C) 2015 STMicroelectronics (R&D) Limited
+ *
+ * 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
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+
+/* Registers */
+#define ST_RNG_STATUS_REG 0x20
+#define ST_RNG_DATA_REG0x24
+
+/* Registers fields */
+#define ST_RNG_STATUS_BAD_SEQUENCE BIT(0)
+#define ST_RNG_STATUS_BAD_ALTERNANCE BIT(1)
+#define ST_RNG_STATUS_FIFO_FULLBIT(5)
+
+#define ST_RNG_FIFO_SIZE 8
+#define ST_RNG_SAMPLE_SIZE 2 /* 2 Byte (16bit) samples */
+
+/* Samples are available every 0.667us, which we round to 1us */
+#define ST_RNG_FILL_FIFO_TIMEOUT (1 * (ST_RNG_FIFO_SIZE /
ST_RNG_SAMPLE_SIZE))
+
+struct st_rng_data {
+ void __iomem*base;
+ struct clk *clk;
+ struct hwrngops;
+};
+
+static int st_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+ struct st_rng_data *ddata = (struct st_rng_data *)rng->priv;
+ u32 status;
+ int i;
+
+ if (max < sizeof(u16))
+ return -EINVAL;
+
+ /* Wait until FIFO is full - max 4uS*/
+ for (i = 0; i < ST_RNG_FILL_FIFO_TIMEOUT; i++) {
+ status = readl_relaxed(ddata->base + ST_RNG_STATUS_REG);
+ if (status & ST_RNG_STATUS_FIFO_FULL)
+ break;
+ udelay(1);
How much bandwidth does using udelay() cost? I think it could be >10%
compared to a tighter polling loop.
+ }
+
+ if (i == ST_RNG_FILL_FIFO_TIMEOUT)
+ return 0;
Isn't a timeout an error condition?
+
+ for (i = 0; i < ST_RNG_FIFO_SIZE && i < max; i += 2)
+ *(u16 *)(data + i) =
+ readl_relaxed(ddata->base + ST_RNG_DATA_REG);
+
+ return i; /* No of bytes read */
+}
+
+static int st_rng_probe(struct platform_device *pdev)
+{
+ struct st_rng_data *ddata;
+ struct resource *res;
+ struct clk *clk;
+ void __iomem *base;
+ int ret;
+
+ ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
+ if (!ddata)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+
+ ret = clk_prepare_enable(clk);
+ if (ret)
+ return ret;
+
+ ddata->ops.priv = (unsigned long)ddata;
+ ddata->ops.read = st_rng_read;
+ ddata->ops.name = pdev->name;
+ ddata->base = base;
+ ddata->clk = clk;
+
+ dev_set_drvdata(&pdev->dev, ddata);
+
+ ret = hwrng_register(&ddata->ops);
+ if (ret) {
+ dev_err(&pdev->dev, "Failed to register HW RNG\n");
Why shout about this particular error but not any others? Perhaps just
rely on the driver core to report the error here?
+ return ret;
+ }
+
+ dev_info(&pdev->dev, "Successfully registered HW RNG\n");
+
+ return 0;
+}
+
+static int st_rng_remove(struct platform_device *pdev)
+{
+ struct st_rng_data *ddata = dev_get_drvdata(&pdev->dev);
+
+ hwrng_unregister(&ddata->ops);
+
+ clk_disable_unprepare(ddata->clk);
This mismatches the error paths in the probe function (there is no
cleanup of clock counts in probe function).
Daniel.
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Re: [PATCH v2 5/7] hwrng: st: Add support for ST's HW Random Number Generator
On 17 September 2015 at 14:45, Lee Jones wrote:
> Signed-off-by: Pankaj Dev
> Signed-off-by: Lee Jones
Comments addressed, Also LGTM.
Acked-by: Kieran Bingham
> ---
> drivers/char/hw_random/Kconfig | 10 +++
> drivers/char/hw_random/Makefile | 1 +
> drivers/char/hw_random/st-rng.c | 144
>
> 3 files changed, 155 insertions(+)
> create mode 100644 drivers/char/hw_random/st-rng.c
>
> diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
> index 8998108..ba5406b 100644
> --- a/drivers/char/hw_random/Kconfig
> +++ b/drivers/char/hw_random/Kconfig
> @@ -346,6 +346,16 @@ config HW_RANDOM_MSM
>
> If unsure, say Y.
>
> +config HW_RANDOM_ST
> + tristate "ST Microelectronics HW Random Number Generator support"
> + depends on HW_RANDOM && ARCH_STI
> + ---help---
> + This driver provides kernel-side support for the Random Number
> + Generator hardware found on STi series of SoCs.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called st-rng.
> +
> config HW_RANDOM_XGENE
> tristate "APM X-Gene True Random Number Generator (TRNG) support"
> depends on HW_RANDOM && ARCH_XGENE
> diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
> index 055bb01..8bcfb45 100644
> --- a/drivers/char/hw_random/Makefile
> +++ b/drivers/char/hw_random/Makefile
> @@ -30,4 +30,5 @@ obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
> obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
> obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
> obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
> +obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
> obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
> diff --git a/drivers/char/hw_random/st-rng.c b/drivers/char/hw_random/st-rng.c
> new file mode 100644
> index 000..8c8a435
> --- /dev/null
> +++ b/drivers/char/hw_random/st-rng.c
> @@ -0,0 +1,144 @@
> +/*
> + * ST Random Number Generator Driver ST's Platforms
> + *
> + * Author: Pankaj Dev:
> + * Lee Jones
> + *
> + * Copyright (C) 2015 STMicroelectronics (R&D) Limited
> + *
> + * 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
> +#include
> +#include
> +#include
> +#include
> +#include
> +#include
> +#include
> +
> +/* Registers */
> +#define ST_RNG_STATUS_REG 0x20
> +#define ST_RNG_DATA_REG0x24
> +
> +/* Registers fields */
> +#define ST_RNG_STATUS_BAD_SEQUENCE BIT(0)
> +#define ST_RNG_STATUS_BAD_ALTERNANCE BIT(1)
> +#define ST_RNG_STATUS_FIFO_FULLBIT(5)
> +
> +#define ST_RNG_FIFO_SIZE 8
> +#define ST_RNG_SAMPLE_SIZE 2 /* 2 Byte (16bit) samples */
> +
> +/* Samples are available every 0.667us, which we round to 1us */
> +#define ST_RNG_FILL_FIFO_TIMEOUT (1 * (ST_RNG_FIFO_SIZE /
> ST_RNG_SAMPLE_SIZE))
> +
> +struct st_rng_data {
> + void __iomem*base;
> + struct clk *clk;
> + struct hwrngops;
> +};
> +
> +static int st_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
> +{
> + struct st_rng_data *ddata = (struct st_rng_data *)rng->priv;
> + u32 status;
> + int i;
> +
> + if (max < sizeof(u16))
> + return -EINVAL;
> +
> + /* Wait until FIFO is full - max 4uS*/
> + for (i = 0; i < ST_RNG_FILL_FIFO_TIMEOUT; i++) {
> + status = readl_relaxed(ddata->base + ST_RNG_STATUS_REG);
> + if (status & ST_RNG_STATUS_FIFO_FULL)
> + break;
> + udelay(1);
> + }
> +
> + if (i == ST_RNG_FILL_FIFO_TIMEOUT)
> + return 0;
> +
> + for (i = 0; i < ST_RNG_FIFO_SIZE && i < max; i += 2)
> + *(u16 *)(data + i) =
> + readl_relaxed(ddata->base + ST_RNG_DATA_REG);
> +
> + return i; /* No of bytes read */
> +}
> +
> +static int st_rng_probe(struct platform_device *pdev)
> +{
> + struct st_rng_data *ddata;
> + struct resource *res;
> + struct clk *clk;
> + void __iomem *base;
> + int ret;
> +
> + ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
> + if (!ddata)
> + return -ENOMEM;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(base))
> + return PTR_ERR(base);
> +
> + clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(clk))
> + return PTR_ERR(clk);
> +
> + ret = clk_prepare_enable(clk);
> + if (ret)
> + return ret;
> +
> + ddata->ops.priv = (unsigned long)ddata;
> + ddata->ops.read = st_rng_read;
> + ddata->ops.name = pdev->name;
> + ddata->base
[PATCH v2 5/7] hwrng: st: Add support for ST's HW Random Number Generator
Signed-off-by: Pankaj Dev
Signed-off-by: Lee Jones
---
drivers/char/hw_random/Kconfig | 10 +++
drivers/char/hw_random/Makefile | 1 +
drivers/char/hw_random/st-rng.c | 144
3 files changed, 155 insertions(+)
create mode 100644 drivers/char/hw_random/st-rng.c
diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 8998108..ba5406b 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -346,6 +346,16 @@ config HW_RANDOM_MSM
If unsure, say Y.
+config HW_RANDOM_ST
+ tristate "ST Microelectronics HW Random Number Generator support"
+ depends on HW_RANDOM && ARCH_STI
+ ---help---
+ This driver provides kernel-side support for the Random Number
+ Generator hardware found on STi series of SoCs.
+
+ To compile this driver as a module, choose M here: the
+ module will be called st-rng.
+
config HW_RANDOM_XGENE
tristate "APM X-Gene True Random Number Generator (TRNG) support"
depends on HW_RANDOM && ARCH_XGENE
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 055bb01..8bcfb45 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -30,4 +30,5 @@ obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
+obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
diff --git a/drivers/char/hw_random/st-rng.c b/drivers/char/hw_random/st-rng.c
new file mode 100644
index 000..8c8a435
--- /dev/null
+++ b/drivers/char/hw_random/st-rng.c
@@ -0,0 +1,144 @@
+/*
+ * ST Random Number Generator Driver ST's Platforms
+ *
+ * Author: Pankaj Dev:
+ * Lee Jones
+ *
+ * Copyright (C) 2015 STMicroelectronics (R&D) Limited
+ *
+ * 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
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+
+/* Registers */
+#define ST_RNG_STATUS_REG 0x20
+#define ST_RNG_DATA_REG0x24
+
+/* Registers fields */
+#define ST_RNG_STATUS_BAD_SEQUENCE BIT(0)
+#define ST_RNG_STATUS_BAD_ALTERNANCE BIT(1)
+#define ST_RNG_STATUS_FIFO_FULLBIT(5)
+
+#define ST_RNG_FIFO_SIZE 8
+#define ST_RNG_SAMPLE_SIZE 2 /* 2 Byte (16bit) samples */
+
+/* Samples are available every 0.667us, which we round to 1us */
+#define ST_RNG_FILL_FIFO_TIMEOUT (1 * (ST_RNG_FIFO_SIZE /
ST_RNG_SAMPLE_SIZE))
+
+struct st_rng_data {
+ void __iomem*base;
+ struct clk *clk;
+ struct hwrngops;
+};
+
+static int st_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+ struct st_rng_data *ddata = (struct st_rng_data *)rng->priv;
+ u32 status;
+ int i;
+
+ if (max < sizeof(u16))
+ return -EINVAL;
+
+ /* Wait until FIFO is full - max 4uS*/
+ for (i = 0; i < ST_RNG_FILL_FIFO_TIMEOUT; i++) {
+ status = readl_relaxed(ddata->base + ST_RNG_STATUS_REG);
+ if (status & ST_RNG_STATUS_FIFO_FULL)
+ break;
+ udelay(1);
+ }
+
+ if (i == ST_RNG_FILL_FIFO_TIMEOUT)
+ return 0;
+
+ for (i = 0; i < ST_RNG_FIFO_SIZE && i < max; i += 2)
+ *(u16 *)(data + i) =
+ readl_relaxed(ddata->base + ST_RNG_DATA_REG);
+
+ return i; /* No of bytes read */
+}
+
+static int st_rng_probe(struct platform_device *pdev)
+{
+ struct st_rng_data *ddata;
+ struct resource *res;
+ struct clk *clk;
+ void __iomem *base;
+ int ret;
+
+ ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
+ if (!ddata)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+
+ ret = clk_prepare_enable(clk);
+ if (ret)
+ return ret;
+
+ ddata->ops.priv = (unsigned long)ddata;
+ ddata->ops.read = st_rng_read;
+ ddata->ops.name = pdev->name;
+ ddata->base = base;
+ ddata->clk = clk;
+
+ dev_set_drvdata(&pdev->dev, ddata);
+
+ ret = hwrng_register(&ddata->ops);
+ if (ret) {
+ dev_err(&pdev->dev, "Failed to register HW RNG\n");
+ return ret;
+ }
+
+ dev_info(&pdev->dev, "Successfully registered HW RNG\n");
+
+ return 0;
+}
+
+static int st_rng_remove(struct platform_device *
