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Date: Thu, 3 Oct 2013 17:52:35 +0300
From: Stanimir Varbanov <svarbanov@...sol.com>
To: Rob Herring <rob.herring@...xeda.com>,
Pawel Moll <pawel.moll@....com>,
Mark Rutland <mark.rutland@....com>,
Stephen Warren <swarren@...dotorg.org>,
Ian Campbell <ijc+devicetree@...lion.org.uk>,
Matt Mackall <mpm@...enic.com>,
Herbert Xu <herbert@...dor.apana.org.au>
Cc: linux-kernel@...r.kernel.org, Rob Landley <rob@...dley.net>,
devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-arm-msm@...r.kernel.org,
Stanimir Varbanov <svarbanov@...sol.com>
Subject: [PATCH 2/2] hwrng: msm: Add PRNG support for MSM SoC's
This adds a driver for hardware random number generator present
on Qualcomm MSM SoC's.
Signed-off-by: Stanimir Varbanov <svarbanov@...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
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");
--
1.8.3.1
--
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