diff mbox

[2/2] hwrng: msm: Add PRNG support for MSM SoC's

Message ID 1380811955-18085-3-git-send-email-svarbanov@mm-sol.com (mailing list archive)
State Not Applicable, archived
Headers show

Commit Message

Stanimir Varbanov Oct. 3, 2013, 2:52 p.m. UTC 
This adds a driver for hardware random number generator present
on Qualcomm MSM SoC's.

Signed-off-by: Stanimir Varbanov <svarbanov@mm-sol.com>
---
 drivers/char/hw_random/Kconfig   |  12 +++
 drivers/char/hw_random/Makefile  |   1 +
 drivers/char/hw_random/msm-rng.c | 211 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 224 insertions(+)
 create mode 100644 drivers/char/hw_random/msm-rng.c

Comments

Stephen Boyd Oct. 3, 2013, 7:25 p.m. UTC | #1 
On 10/03/13 07:52, Stanimir Varbanov wrote:
> +#define PRNG_CONFIG_MASK	0x00000002
> +#define PRNG_CONFIG_HW_ENABLE	BIT(1)

These two are the same so please drop the PRNG_CONFIG_MASK define and
just use the PRNG_CONFIG_HW_ENABLE define.

> +#define PRNG_STATUS_DATA_AVAIL	BIT(0)
> +
> +#define MAX_HW_FIFO_DEPTH	16
> +#define MAX_HW_FIFO_SIZE	(MAX_HW_FIFO_DEPTH * 4)
> +#define WORD_SZ			4
> +
> +struct msm_rng {
> +	void __iomem *base;
> +	struct clk *clk;
> +};
> +
> +static int msm_rng_enable(struct msm_rng *rng, int enable)
> +{
> +	u32 val;
> +	int ret;
> +
> +	ret = clk_prepare_enable(rng->clk);
> +	if (ret)
> +		return ret;
> +
> +	if (enable) {
> +		/* Enable PRNG only if it is not already enabled */
> +		val = readl_relaxed(rng->base + PRNG_CONFIG);
> +		if (val & PRNG_CONFIG_HW_ENABLE)
> +			goto already_enabled;
> +
> +		/* PRNG is not enabled */
> +		val = readl_relaxed(rng->base + PRNG_LFSR_CFG);
> +		val &= ~PRNG_LFSR_CFG_MASK;
> +		val |= PRNG_LFSR_CFG_CLOCKS;
> +		writel(val, rng->base + PRNG_LFSR_CFG);
> +
> +		val = readl_relaxed(rng->base + PRNG_CONFIG);
> +		val &= ~PRNG_CONFIG_MASK;
> +		val |= PRNG_CONFIG_HW_ENABLE;
> +		writel(val, rng->base + PRNG_CONFIG);

This could just be

		val = readl_relaxed(rng->base + PRNG_CONFIG);
		val |= PRNG_CONFIG_HW_ENABLE;
		writel(val, rng->base + PRNG_CONFIG);


> +	} else {
> +		val = readl_relaxed(rng->base + PRNG_CONFIG);
> +		val &= ~PRNG_CONFIG_MASK;
> +		writel(val, rng->base + PRNG_CONFIG);
> +	}
> +
> +already_enabled:
> +	clk_disable_unprepare(rng->clk);
> +	return 0;
> +}
> +
[...]
> +static int msm_rng_probe(struct platform_device *pdev)
> +{
> +	struct msm_rng *rng;
> +	struct device_node *np;
> +	struct resource res;
> +	int ret;
> +
> +	np = of_node_get(pdev->dev.of_node);
> +	if (!np)
> +		return -ENODEV;

This is unnecessary.

> +
> +	rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
> +	if (!rng) {
> +		ret = -ENOMEM;
> +		goto err_exit;
> +	}
> +
> +	ret = of_address_to_resource(np, 0, &res);
> +	if (ret)
> +		goto err_exit;

We should just do

  res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  rng->base = devm_ioremap_resource(&pdev->dev, res);
  if (IS_ERR(rng->base))
            return PTR_ERR(rng->base);

> +
> +	rng->base = devm_ioremap_resource(&pdev->dev, &res);
> +	if (IS_ERR(rng->base)) {
> +		ret = PTR_ERR(rng->base);
> +		goto err_exit;
> +	}
> +
> +	rng->clk = devm_clk_get(&pdev->dev, "prng");
> +	if (IS_ERR(rng->clk)) {
> +		ret = PTR_ERR(rng->clk);
> +		goto err_exit;
> +	}
> +
> +	msm_rng_ops.priv = (unsigned long) rng;
> +	ret = hwrng_register(&msm_rng_ops);
> +	if (ret)
> +		dev_err(&pdev->dev, "failed to register hwrng\n");
> +
> +err_exit:

Doing all that should make this goto exit path unnecessary.

> +	of_node_put(np);
> +	return ret;
> +}
> +
> +static int msm_rng_remove(struct platform_device *pdev)
> +{
> +	hwrng_unregister(&msm_rng_ops);
> +	return 0;
> +}
> +
> +static struct of_device_id msm_rng_of_match[] = {

const?

> +	{ .compatible = "qcom,prng", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, msm_rng_of_match);
> +
> +static struct platform_driver msm_rng_driver = {
> +	.probe = msm_rng_probe,
> +	.remove = msm_rng_remove,
> +	.driver = {
> +		.name = KBUILD_MODNAME,
> +		.owner = THIS_MODULE,
> +		.of_match_table = of_match_ptr(msm_rng_of_match),
> +	}
> +};
> +module_platform_driver(msm_rng_driver);
> +
> +MODULE_AUTHOR("The Linux Foundation");
> +MODULE_DESCRIPTION("Qualcomm MSM random number generator driver");
> +MODULE_LICENSE("GPL v2");
Stanimir Varbanov Oct. 4, 2013, 4:31 p.m. UTC | #2 
Hi Stephen,

Thanks for the quick review!

On 10/03/2013 10:25 PM, Stephen Boyd wrote:
> On 10/03/13 07:52, Stanimir Varbanov wrote:
>> +#define PRNG_CONFIG_MASK	0x00000002
>> +#define PRNG_CONFIG_HW_ENABLE	BIT(1)
> 
> These two are the same so please drop the PRNG_CONFIG_MASK define and
> just use the PRNG_CONFIG_HW_ENABLE define.
> 

OK I will drop the mask and rework the code related to it.

>> +#define PRNG_STATUS_DATA_AVAIL	BIT(0)
>> +
>> +#define MAX_HW_FIFO_DEPTH	16
>> +#define MAX_HW_FIFO_SIZE	(MAX_HW_FIFO_DEPTH * 4)
>> +#define WORD_SZ			4
>> +
>> +struct msm_rng {
>> +	void __iomem *base;
>> +	struct clk *clk;
>> +};
>> +
>> +static int msm_rng_enable(struct msm_rng *rng, int enable)
>> +{
>> +	u32 val;
>> +	int ret;
>> +
>> +	ret = clk_prepare_enable(rng->clk);
>> +	if (ret)
>> +		return ret;
>> +
>> +	if (enable) {
>> +		/* Enable PRNG only if it is not already enabled */
>> +		val = readl_relaxed(rng->base + PRNG_CONFIG);
>> +		if (val & PRNG_CONFIG_HW_ENABLE)
>> +			goto already_enabled;
>> +
>> +		/* PRNG is not enabled */
>> +		val = readl_relaxed(rng->base + PRNG_LFSR_CFG);
>> +		val &= ~PRNG_LFSR_CFG_MASK;
>> +		val |= PRNG_LFSR_CFG_CLOCKS;
>> +		writel(val, rng->base + PRNG_LFSR_CFG);
>> +
>> +		val = readl_relaxed(rng->base + PRNG_CONFIG);
>> +		val &= ~PRNG_CONFIG_MASK;
>> +		val |= PRNG_CONFIG_HW_ENABLE;
>> +		writel(val, rng->base + PRNG_CONFIG);
> 
> This could just be
> 
> 		val = readl_relaxed(rng->base + PRNG_CONFIG);
> 		val |= PRNG_CONFIG_HW_ENABLE;
> 		writel(val, rng->base + PRNG_CONFIG);
> 
> 
>> +	} else {
>> +		val = readl_relaxed(rng->base + PRNG_CONFIG);
>> +		val &= ~PRNG_CONFIG_MASK;
>> +		writel(val, rng->base + PRNG_CONFIG);
>> +	}
>> +
>> +already_enabled:
>> +	clk_disable_unprepare(rng->clk);
>> +	return 0;
>> +}
>> +
> [...]
>> +static int msm_rng_probe(struct platform_device *pdev)
>> +{
>> +	struct msm_rng *rng;
>> +	struct device_node *np;
>> +	struct resource res;
>> +	int ret;
>> +
>> +	np = of_node_get(pdev->dev.of_node);
>> +	if (!np)
>> +		return -ENODEV;
> 
> This is unnecessary.

I used this call because CONFIG_OF_DYNAMIC could be enabled at some
time. Isn't that possible? I saw that of_node_get|put is used in .probe
on few places in drivers.

> 
>> +
>> +	rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
>> +	if (!rng) {
>> +		ret = -ENOMEM;
>> +		goto err_exit;
>> +	}
>> +
>> +	ret = of_address_to_resource(np, 0, &res);
>> +	if (ret)
>> +		goto err_exit;
> 
> We should just do
> 
>   res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>   rng->base = devm_ioremap_resource(&pdev->dev, res);
>   if (IS_ERR(rng->base))
>             return PTR_ERR(rng->base);
> 
>> +
>> +	rng->base = devm_ioremap_resource(&pdev->dev, &res);
>> +	if (IS_ERR(rng->base)) {
>> +		ret = PTR_ERR(rng->base);
>> +		goto err_exit;
>> +	}
>> +
>> +	rng->clk = devm_clk_get(&pdev->dev, "prng");
>> +	if (IS_ERR(rng->clk)) {
>> +		ret = PTR_ERR(rng->clk);
>> +		goto err_exit;
>> +	}
>> +
>> +	msm_rng_ops.priv = (unsigned long) rng;
>> +	ret = hwrng_register(&msm_rng_ops);
>> +	if (ret)
>> +		dev_err(&pdev->dev, "failed to register hwrng\n");
>> +
>> +err_exit:
> 
> Doing all that should make this goto exit path unnecessary.
> 
>> +	of_node_put(np);
>> +	return ret;
>> +}
>> +
>> +static int msm_rng_remove(struct platform_device *pdev)
>> +{
>> +	hwrng_unregister(&msm_rng_ops);
>> +	return 0;
>> +}
>> +
>> +static struct of_device_id msm_rng_of_match[] = {
> 
> const?
> 
>> +	{ .compatible = "qcom,prng", },
>> +	{}
>> +};
>> +MODULE_DEVICE_TABLE(of, msm_rng_of_match);
>> +
>> +static struct platform_driver msm_rng_driver = {
>> +	.probe = msm_rng_probe,
>> +	.remove = msm_rng_remove,
>> +	.driver = {
>> +		.name = KBUILD_MODNAME,
>> +		.owner = THIS_MODULE,
>> +		.of_match_table = of_match_ptr(msm_rng_of_match),
>> +	}
>> +};
>> +module_platform_driver(msm_rng_driver);
>> +
>> +MODULE_AUTHOR("The Linux Foundation");
>> +MODULE_DESCRIPTION("Qualcomm MSM random number generator driver");
>> +MODULE_LICENSE("GPL v2");
> 
> 

regards,
Stan

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Stephen Boyd Oct. 4, 2013, 4:37 p.m. UTC | #3 
On 10/04/13 09:31, Stanimir Varbanov wrote:
>
>>> +static int msm_rng_probe(struct platform_device *pdev)
>>> +{
>>> +	struct msm_rng *rng;
>>> +	struct device_node *np;
>>> +	struct resource res;
>>> +	int ret;
>>> +
>>> +	np = of_node_get(pdev->dev.of_node);
>>> +	if (!np)
>>> +		return -ENODEV;
>> This is unnecessary.
> I used this call because CONFIG_OF_DYNAMIC could be enabled at some
> time. Isn't that possible? I saw that of_node_get|put is used in .probe
> on few places in drivers.

So far we aren't selecting that config on ARM.

If you look at of_device_alloc() you'll see

    dev->dev.of_node = of_node_get(np);

so any platform devices created from of_platform_populate won't have
their of_node go away.
Stanimir Varbanov Oct. 9, 2013, 8:23 a.m. UTC | #4 
Hi Stephen,

On 10/04/2013 07:37 PM, Stephen Boyd wrote:
> On 10/04/13 09:31, Stanimir Varbanov wrote:
>>
>>>> +static int msm_rng_probe(struct platform_device *pdev)
>>>> +{
>>>> +	struct msm_rng *rng;
>>>> +	struct device_node *np;
>>>> +	struct resource res;
>>>> +	int ret;
>>>> +
>>>> +	np = of_node_get(pdev->dev.of_node);
>>>> +	if (!np)
>>>> +		return -ENODEV;
>>> This is unnecessary.
>> I used this call because CONFIG_OF_DYNAMIC could be enabled at some
>> time. Isn't that possible? I saw that of_node_get|put is used in .probe
>> on few places in drivers.
> 
> So far we aren't selecting that config on ARM.
> 
> If you look at of_device_alloc() you'll see
> 
>     dev->dev.of_node = of_node_get(np);
> 
> so any platform devices created from of_platform_populate won't have
> their of_node go away.

Thanks for the pointers, it makes sense. I'll remove the calls to
of_node_get|put.

regards,
Stan


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diff mbox

Patch

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 0aa9d91daef5..d902330cef43 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -314,3 +314,15 @@  config HW_RANDOM_TPM
 	  module will be called tpm-rng.
 
 	  If unsure, say Y.
+
+config HW_RANDOM_MSM
+        tristate "Qualcomm MSM Random Number Generator support"
+        depends on HW_RANDOM && ARCH_MSM && HAVE_CLK
+        ---help---
+          This driver provides kernel-side support for the Random Number
+          Generator hardware found on Qualcomm MSM SoCs.
+
+          To compile this driver as a module, choose M here. the
+          module will be called msm-rng.
+
+          If unsure, say Y.
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index bed467c9300e..441a0a7705a2 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -27,3 +27,4 @@  obj-$(CONFIG_HW_RANDOM_PSERIES) += pseries-rng.o
 obj-$(CONFIG_HW_RANDOM_EXYNOS)	+= exynos-rng.o
 obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
 obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
+obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
diff --git a/drivers/char/hw_random/msm-rng.c b/drivers/char/hw_random/msm-rng.c
new file mode 100644
index 000000000000..c4545d2da949
--- /dev/null
+++ b/drivers/char/hw_random/msm-rng.c
@@ -0,0 +1,211 @@ 
+/*
+ * Copyright (c) 2011-2013, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+#include <linux/clk.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+
+/* Device specific register offsets */
+#define PRNG_DATA_OUT		0x0000
+#define PRNG_STATUS		0x0004
+#define PRNG_LFSR_CFG		0x0100
+#define PRNG_CONFIG		0x0104
+
+/* Device specific register masks and config values */
+#define PRNG_LFSR_CFG_MASK	0x0000ffff
+#define PRNG_LFSR_CFG_CLOCKS	0x0000dddd
+#define PRNG_CONFIG_MASK	0x00000002
+#define PRNG_CONFIG_HW_ENABLE	BIT(1)
+#define PRNG_STATUS_DATA_AVAIL	BIT(0)
+
+#define MAX_HW_FIFO_DEPTH	16
+#define MAX_HW_FIFO_SIZE	(MAX_HW_FIFO_DEPTH * 4)
+#define WORD_SZ			4
+
+struct msm_rng {
+	void __iomem *base;
+	struct clk *clk;
+};
+
+static int msm_rng_enable(struct msm_rng *rng, int enable)
+{
+	u32 val;
+	int ret;
+
+	ret = clk_prepare_enable(rng->clk);
+	if (ret)
+		return ret;
+
+	if (enable) {
+		/* Enable PRNG only if it is not already enabled */
+		val = readl_relaxed(rng->base + PRNG_CONFIG);
+		if (val & PRNG_CONFIG_HW_ENABLE)
+			goto already_enabled;
+
+		/* PRNG is not enabled */
+		val = readl_relaxed(rng->base + PRNG_LFSR_CFG);
+		val &= ~PRNG_LFSR_CFG_MASK;
+		val |= PRNG_LFSR_CFG_CLOCKS;
+		writel(val, rng->base + PRNG_LFSR_CFG);
+
+		val = readl_relaxed(rng->base + PRNG_CONFIG);
+		val &= ~PRNG_CONFIG_MASK;
+		val |= PRNG_CONFIG_HW_ENABLE;
+		writel(val, rng->base + PRNG_CONFIG);
+	} else {
+		val = readl_relaxed(rng->base + PRNG_CONFIG);
+		val &= ~PRNG_CONFIG_MASK;
+		writel(val, rng->base + PRNG_CONFIG);
+	}
+
+already_enabled:
+	clk_disable_unprepare(rng->clk);
+	return 0;
+}
+
+static int msm_rng_read(struct hwrng *hwrng, void *data, size_t max, bool wait)
+{
+	struct msm_rng *rng = (struct msm_rng *)hwrng->priv;
+	size_t currsize = 0;
+	u32 *retdata = data;
+	size_t maxsize;
+	int ret;
+	u32 val;
+
+	/* calculate max size bytes to transfer back to caller */
+	maxsize = min_t(size_t, MAX_HW_FIFO_SIZE, max);
+
+	/* no room for word data */
+	if (maxsize < WORD_SZ)
+		return 0;
+
+	ret = clk_prepare_enable(rng->clk);
+	if (ret)
+		return ret;
+
+	/* read random data from hardware */
+	do {
+		val = readl_relaxed(rng->base + PRNG_STATUS);
+		if (!(val & PRNG_STATUS_DATA_AVAIL))
+			break;
+
+		val = readl_relaxed(rng->base + PRNG_DATA_OUT);
+		if (!val)
+			break;
+
+		*retdata++ = val;
+		currsize += WORD_SZ;
+
+		/* make sure we stay on 32bit boundary */
+		if ((maxsize - currsize) < WORD_SZ)
+			break;
+	} while (currsize < maxsize);
+
+	clk_disable_unprepare(rng->clk);
+
+	return currsize;
+}
+
+static int msm_rng_init(struct hwrng *hwrng)
+{
+	struct msm_rng *rng = (struct msm_rng *)hwrng->priv;
+
+	return msm_rng_enable(rng, 1);
+}
+
+static void msm_rng_cleanup(struct hwrng *hwrng)
+{
+	struct msm_rng *rng = (struct msm_rng *)hwrng->priv;
+
+	msm_rng_enable(rng, 0);
+}
+
+static struct hwrng msm_rng_ops = {
+	.name = KBUILD_MODNAME,
+	.init = msm_rng_init,
+	.cleanup = msm_rng_cleanup,
+	.read = msm_rng_read,
+};
+
+static int msm_rng_probe(struct platform_device *pdev)
+{
+	struct msm_rng *rng;
+	struct device_node *np;
+	struct resource res;
+	int ret;
+
+	np = of_node_get(pdev->dev.of_node);
+	if (!np)
+		return -ENODEV;
+
+	rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
+	if (!rng) {
+		ret = -ENOMEM;
+		goto err_exit;
+	}
+
+	ret = of_address_to_resource(np, 0, &res);
+	if (ret)
+		goto err_exit;
+
+	rng->base = devm_ioremap_resource(&pdev->dev, &res);
+	if (IS_ERR(rng->base)) {
+		ret = PTR_ERR(rng->base);
+		goto err_exit;
+	}
+
+	rng->clk = devm_clk_get(&pdev->dev, "prng");
+	if (IS_ERR(rng->clk)) {
+		ret = PTR_ERR(rng->clk);
+		goto err_exit;
+	}
+
+	msm_rng_ops.priv = (unsigned long) rng;
+	ret = hwrng_register(&msm_rng_ops);
+	if (ret)
+		dev_err(&pdev->dev, "failed to register hwrng\n");
+
+err_exit:
+	of_node_put(np);
+	return ret;
+}
+
+static int msm_rng_remove(struct platform_device *pdev)
+{
+	hwrng_unregister(&msm_rng_ops);
+	return 0;
+}
+
+static struct of_device_id msm_rng_of_match[] = {
+	{ .compatible = "qcom,prng", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, msm_rng_of_match);
+
+static struct platform_driver msm_rng_driver = {
+	.probe = msm_rng_probe,
+	.remove = msm_rng_remove,
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(msm_rng_of_match),
+	}
+};
+module_platform_driver(msm_rng_driver);
+
+MODULE_AUTHOR("The Linux Foundation");
+MODULE_DESCRIPTION("Qualcomm MSM random number generator driver");
+MODULE_LICENSE("GPL v2");