From 4a4da53c408c9e1e545b60d2b07635d08a949c99 Mon Sep 17 00:00:00 2001 From: Lee Jones Date: Thu, 17 Sep 2015 14:45:55 +0100 Subject: [PATCH] hwrng: st - Add support for ST's HW Random Number Generator Signed-off-by: Pankaj Dev Signed-off-by: Lee Jones Acked-by: Kieran Bingham Signed-off-by: Herbert Xu --- 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 8998108f9721..ba5406b9a072 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 055bb01510ad..8bcfb45af2ec 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 000000000000..8c8a435176e8 --- /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_ALTERNANCE BIT(1) +#define ST_RNG_STATUS_FIFO_FULL BIT(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 hwrng ops; +}; + +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 *pdev) +{ + struct st_rng_data *ddata = dev_get_drvdata(&pdev->dev); + + hwrng_unregister(&ddata->ops); + + clk_disable_unprepare(ddata->clk); + + return 0; +} + +static const struct of_device_id st_rng_match[] = { + { .compatible = "st,rng" }, + {}, +}; +MODULE_DEVICE_TABLE(of, st_rng_match); + +static struct platform_driver st_rng_driver = { + .driver = { + .name = "st-hwrandom", + .of_match_table = of_match_ptr(st_rng_match), + }, + .probe = st_rng_probe, + .remove = st_rng_remove +}; + +module_platform_driver(st_rng_driver); + +MODULE_AUTHOR("Pankaj Dev "); +MODULE_LICENSE("GPL v2"); -- 2.39.2