diff options
Diffstat (limited to 'drivers/char/hw_random/ks-sa-rng.c')
| -rw-r--r-- | drivers/char/hw_random/ks-sa-rng.c | 258 |
1 files changed, 258 insertions, 0 deletions
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 000000000..b6d7db362 --- /dev/null +++ b/drivers/char/hw_random/ks-sa-rng.c @@ -0,0 +1,258 @@ +/* + * 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_put_noidle(dev); + 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"); |