diff options
author | José Pekkarinen <jose.pekkarinen@nokia.com> | 2016-04-11 10:41:07 +0300 |
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committer | José Pekkarinen <jose.pekkarinen@nokia.com> | 2016-04-13 08:17:18 +0300 |
commit | e09b41010ba33a20a87472ee821fa407a5b8da36 (patch) | |
tree | d10dc367189862e7ca5c592f033dc3726e1df4e3 /kernel/drivers/char/hw_random/st-rng.c | |
parent | f93b97fd65072de626c074dbe099a1fff05ce060 (diff) |
These changes are the raw update to linux-4.4.6-rt14. Kernel sources
are taken from kernel.org, and rt patch from the rt wiki download page.
During the rebasing, the following patch collided:
Force tick interrupt and get rid of softirq magic(I70131fb85).
Collisions have been removed because its logic was found on the
source already.
Change-Id: I7f57a4081d9deaa0d9ccfc41a6c8daccdee3b769
Signed-off-by: José Pekkarinen <jose.pekkarinen@nokia.com>
Diffstat (limited to 'kernel/drivers/char/hw_random/st-rng.c')
-rw-r--r-- | kernel/drivers/char/hw_random/st-rng.c | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/kernel/drivers/char/hw_random/st-rng.c b/kernel/drivers/char/hw_random/st-rng.c new file mode 100644 index 000000000..1d35363d2 --- /dev/null +++ b/kernel/drivers/char/hw_random/st-rng.c @@ -0,0 +1,151 @@ +/* + * ST Random Number Generator Driver ST's Platforms + * + * Author: Pankaj Dev: <pankaj.dev@st.com> + * Lee Jones <lee.jones@linaro.org> + * + * 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 <linux/clk.h> +#include <linux/delay.h> +#include <linux/hw_random.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/slab.h> + +/* 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_SAMPLE_SIZE 2 /* 2 Byte (16bit) samples */ +#define ST_RNG_FIFO_DEPTH 4 +#define ST_RNG_FIFO_SIZE (ST_RNG_FIFO_DEPTH * ST_RNG_SAMPLE_SIZE) + +/* + * Samples are documented to be available every 0.667us, so in theory + * the 4 sample deep FIFO should take 2.668us to fill. However, during + * thorough testing, it became apparent that filling the FIFO actually + * takes closer to 12us. We then multiply by 2 in order to account for + * the lack of udelay()'s reliability, suggested by Russell King. + */ +#define ST_RNG_FILL_FIFO_TIMEOUT (12 * 2) + +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 <pankaj.dev@st.com>"); +MODULE_LICENSE("GPL v2"); |