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Subject[PATCH v2 2/2] hw_random: keystone2: add hw_random driver
Date
Keystone Security Accelerator module has a hardware random generator
sub-module. This commit adds the driver for this sub-module.

Signed-off-by: Vitaly Andrianov <vitalya@ti.com>
[t-kristo@ti.com: dropped one unnecessary dev_err message]
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
---
drivers/char/hw_random/Kconfig | 7 +
drivers/char/hw_random/Makefile | 1 +
drivers/char/hw_random/ks-sa-rng.c | 257 +++++++++++++++++++++++++++++++++++++
3 files changed, 265 insertions(+)
create mode 100644 drivers/char/hw_random/ks-sa-rng.c

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 4d0f571..d53541e 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -452,3 +452,10 @@ config UML_RANDOM
(check your distro, or download from
http://sourceforge.net/projects/gkernel/). rngd periodically reads
/dev/hwrng and injects the entropy into /dev/random.
+
+config HW_RANDOM_KEYSTONE
+ depends on ARCH_KEYSTONE
+ default HW_RANDOM
+ tristate "TI Keystone NETCP SA Hardware random number generator"
+ help
+ This option enables Keystone's hardware random generator.
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index b780370..533e913 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -38,3 +38,4 @@ obj-$(CONFIG_HW_RANDOM_MESON) += meson-rng.o
obj-$(CONFIG_HW_RANDOM_CAVIUM) += cavium-rng.o cavium-rng-vf.o
obj-$(CONFIG_HW_RANDOM_MTK) += mtk-rng.o
obj-$(CONFIG_HW_RANDOM_S390) += s390-trng.o
+obj-$(CONFIG_HW_RANDOM_KEYSTONE) += ks-sa-rng.o
diff --git a/drivers/char/hw_random/ks-sa-rng.c b/drivers/char/hw_random/ks-sa-rng.c
new file mode 100644
index 0000000..62c6696
--- /dev/null
+++ b/drivers/char/hw_random/ks-sa-rng.c
@@ -0,0 +1,257 @@
+/*
+ * Random Number Generator driver for the Keystone SOC
+ *
+ * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Authors: Sandeep Nair
+ * Vitaly Andrianov
+ *
+ * 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.
+ *
+ * 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/hw_random.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/pm_runtime.h>
+#include <linux/err.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/delay.h>
+
+#define SA_CMD_STATUS_OFS 0x8
+
+/* TRNG enable control in SA System module*/
+#define SA_CMD_STATUS_REG_TRNG_ENABLE BIT(3)
+
+/* TRNG start control in TRNG module */
+#define TRNG_CNTL_REG_TRNG_ENABLE BIT(10)
+
+/* Data ready indicator in STATUS register */
+#define TRNG_STATUS_REG_READY BIT(0)
+
+/* Data ready clear control in INTACK register */
+#define TRNG_INTACK_REG_READY BIT(0)
+
+/*
+ * Number of samples taken to gather entropy during startup.
+ * If value is 0, the number of samples is 2^24 else
+ * equals value times 2^8.
+ */
+#define TRNG_DEF_STARTUP_CYCLES 0
+#define TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT 16
+
+/*
+ * Minimum number of samples taken to regenerate entropy
+ * If value is 0, the number of samples is 2^24 else
+ * equals value times 2^6.
+ */
+#define TRNG_DEF_MIN_REFILL_CYCLES 1
+#define TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT 0
+
+/*
+ * Maximum number of samples taken to regenerate entropy
+ * If value is 0, the number of samples is 2^24 else
+ * equals value times 2^8.
+ */
+#define TRNG_DEF_MAX_REFILL_CYCLES 0
+#define TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT 16
+
+/* Number of CLK input cycles between samples */
+#define TRNG_DEF_CLK_DIV_CYCLES 0
+#define TRNG_CFG_REG_SAMPLE_DIV_SHIFT 8
+
+/* Maximum retries to get rng data */
+#define SA_MAX_RNG_DATA_RETRIES 5
+/* Delay between retries (in usecs) */
+#define SA_RNG_DATA_RETRY_DELAY 5
+
+struct trng_regs {
+ u32 output_l;
+ u32 output_h;
+ u32 status;
+ u32 intmask;
+ u32 intack;
+ u32 control;
+ u32 config;
+};
+
+struct ks_sa_rng {
+ struct device *dev;
+ struct hwrng rng;
+ struct clk *clk;
+ struct regmap *regmap_cfg;
+ struct trng_regs *reg_rng;
+};
+
+static int ks_sa_rng_init(struct hwrng *rng)
+{
+ u32 value;
+ struct device *dev = (struct device *)rng->priv;
+ struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
+
+ /* Enable RNG module */
+ regmap_write_bits(ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,
+ SA_CMD_STATUS_REG_TRNG_ENABLE,
+ SA_CMD_STATUS_REG_TRNG_ENABLE);
+
+ /* Configure RNG module */
+ writel(0, &ks_sa_rng->reg_rng->control);
+ value = TRNG_DEF_STARTUP_CYCLES << TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT;
+ writel(value, &ks_sa_rng->reg_rng->control);
+
+ value = (TRNG_DEF_MIN_REFILL_CYCLES <<
+ TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT) |
+ (TRNG_DEF_MAX_REFILL_CYCLES <<
+ TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT) |
+ (TRNG_DEF_CLK_DIV_CYCLES <<
+ TRNG_CFG_REG_SAMPLE_DIV_SHIFT);
+
+ writel(value, &ks_sa_rng->reg_rng->config);
+
+ /* Disable all interrupts from TRNG */
+ writel(0, &ks_sa_rng->reg_rng->intmask);
+
+ /* Enable RNG */
+ value = readl(&ks_sa_rng->reg_rng->control);
+ value |= TRNG_CNTL_REG_TRNG_ENABLE;
+ writel(value, &ks_sa_rng->reg_rng->control);
+
+ return 0;
+}
+
+static void ks_sa_rng_cleanup(struct hwrng *rng)
+{
+ struct device *dev = (struct device *)rng->priv;
+ struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
+
+ /* Disable RNG */
+ writel(0, &ks_sa_rng->reg_rng->control);
+ regmap_write_bits(ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,
+ SA_CMD_STATUS_REG_TRNG_ENABLE, 0);
+}
+
+static int ks_sa_rng_data_read(struct hwrng *rng, u32 *data)
+{
+ struct device *dev = (struct device *)rng->priv;
+ struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
+
+ /* Read random data */
+ data[0] = readl(&ks_sa_rng->reg_rng->output_l);
+ data[1] = readl(&ks_sa_rng->reg_rng->output_h);
+
+ writel(TRNG_INTACK_REG_READY, &ks_sa_rng->reg_rng->intack);
+
+ return sizeof(u32) * 2;
+}
+
+static int ks_sa_rng_data_present(struct hwrng *rng, int wait)
+{
+ struct device *dev = (struct device *)rng->priv;
+ struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
+
+ u32 ready;
+ int j;
+
+ for (j = 0; j < SA_MAX_RNG_DATA_RETRIES; j++) {
+ ready = readl(&ks_sa_rng->reg_rng->status);
+ ready &= TRNG_STATUS_REG_READY;
+
+ if (ready || !wait)
+ break;
+
+ udelay(SA_RNG_DATA_RETRY_DELAY);
+ }
+
+ return ready;
+}
+
+static int ks_sa_rng_probe(struct platform_device *pdev)
+{
+ struct ks_sa_rng *ks_sa_rng;
+ struct device *dev = &pdev->dev;
+ int ret;
+ struct resource *mem;
+
+ ks_sa_rng = devm_kzalloc(dev, sizeof(*ks_sa_rng), GFP_KERNEL);
+ if (!ks_sa_rng)
+ return -ENOMEM;
+
+ ks_sa_rng->dev = dev;
+ ks_sa_rng->rng = (struct hwrng) {
+ .name = "ks_sa_hwrng",
+ .init = ks_sa_rng_init,
+ .data_read = ks_sa_rng_data_read,
+ .data_present = ks_sa_rng_data_present,
+ .cleanup = ks_sa_rng_cleanup,
+ };
+ ks_sa_rng->rng.priv = (unsigned long)dev;
+
+ mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ ks_sa_rng->reg_rng = devm_ioremap_resource(dev, mem);
+ if (IS_ERR(ks_sa_rng->reg_rng))
+ return PTR_ERR(ks_sa_rng->reg_rng);
+
+ ks_sa_rng->regmap_cfg =
+ syscon_regmap_lookup_by_phandle(dev->of_node,
+ "ti,syscon-sa-cfg");
+
+ if (IS_ERR(ks_sa_rng->regmap_cfg)) {
+ dev_err(dev, "syscon_node_to_regmap failed\n");
+ return -EINVAL;
+ }
+
+ pm_runtime_enable(dev);
+ ret = pm_runtime_get_sync(dev);
+ if (ret < 0) {
+ dev_err(dev, "Failed to enable SA power-domain\n");
+ pm_runtime_disable(dev);
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, ks_sa_rng);
+
+ return devm_hwrng_register(&pdev->dev, &ks_sa_rng->rng);
+}
+
+static int ks_sa_rng_remove(struct platform_device *pdev)
+{
+ pm_runtime_put_sync(&pdev->dev);
+ pm_runtime_disable(&pdev->dev);
+
+ return 0;
+}
+
+static const struct of_device_id ks_sa_rng_dt_match[] = {
+ {
+ .compatible = "ti,keystone-rng",
+ },
+ { },
+};
+MODULE_DEVICE_TABLE(of, ks_sa_rng_dt_match);
+
+static struct platform_driver ks_sa_rng_driver = {
+ .driver = {
+ .name = "ks-sa-rng",
+ .of_match_table = ks_sa_rng_dt_match,
+ },
+ .probe = ks_sa_rng_probe,
+ .remove = ks_sa_rng_remove,
+};
+
+module_platform_driver(ks_sa_rng_driver);
+
+MODULE_DESCRIPTION("Keystone NETCP SA H/W Random Number Generator driver");
+MODULE_AUTHOR("Vitaly Andrianov <vitalya@ti.com>");
+MODULE_LICENSE("GPL");
--
2.7.4
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