diff options
Diffstat (limited to 'drivers/char/hw_random/imx-rngc.c')
| -rw-r--r-- | drivers/char/hw_random/imx-rngc.c | 344 |
1 files changed, 344 insertions, 0 deletions
diff --git a/drivers/char/hw_random/imx-rngc.c b/drivers/char/hw_random/imx-rngc.c new file mode 100644 index 000000000..75fb46298 --- /dev/null +++ b/drivers/char/hw_random/imx-rngc.c @@ -0,0 +1,344 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * RNG driver for Freescale RNGC + * + * Copyright (C) 2008-2012 Freescale Semiconductor, Inc. + * Copyright (C) 2017 Martin Kaiser <martin@kaiser.cx> + */ + +#include <linux/module.h> +#include <linux/mod_devicetable.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/platform_device.h> +#include <linux/interrupt.h> +#include <linux/hw_random.h> +#include <linux/completion.h> +#include <linux/io.h> + +#define RNGC_VER_ID 0x0000 +#define RNGC_COMMAND 0x0004 +#define RNGC_CONTROL 0x0008 +#define RNGC_STATUS 0x000C +#define RNGC_ERROR 0x0010 +#define RNGC_FIFO 0x0014 + +/* the fields in the ver id register */ +#define RNGC_TYPE_SHIFT 28 +#define RNGC_VER_MAJ_SHIFT 8 + +/* the rng_type field */ +#define RNGC_TYPE_RNGB 0x1 +#define RNGC_TYPE_RNGC 0x2 + + +#define RNGC_CMD_CLR_ERR 0x00000020 +#define RNGC_CMD_CLR_INT 0x00000010 +#define RNGC_CMD_SEED 0x00000002 +#define RNGC_CMD_SELF_TEST 0x00000001 + +#define RNGC_CTRL_MASK_ERROR 0x00000040 +#define RNGC_CTRL_MASK_DONE 0x00000020 +#define RNGC_CTRL_AUTO_SEED 0x00000010 + +#define RNGC_STATUS_ERROR 0x00010000 +#define RNGC_STATUS_FIFO_LEVEL_MASK 0x00000f00 +#define RNGC_STATUS_FIFO_LEVEL_SHIFT 8 +#define RNGC_STATUS_SEED_DONE 0x00000020 +#define RNGC_STATUS_ST_DONE 0x00000010 + +#define RNGC_ERROR_STATUS_STAT_ERR 0x00000008 + +#define RNGC_TIMEOUT 3000 /* 3 sec */ + + +static bool self_test = true; +module_param(self_test, bool, 0); + +struct imx_rngc { + struct device *dev; + struct clk *clk; + void __iomem *base; + struct hwrng rng; + struct completion rng_op_done; + /* + * err_reg is written only by the irq handler and read only + * when interrupts are masked, we need no spinlock + */ + u32 err_reg; +}; + + +static inline void imx_rngc_irq_mask_clear(struct imx_rngc *rngc) +{ + u32 ctrl, cmd; + + /* mask interrupts */ + ctrl = readl(rngc->base + RNGC_CONTROL); + ctrl |= RNGC_CTRL_MASK_DONE | RNGC_CTRL_MASK_ERROR; + writel(ctrl, rngc->base + RNGC_CONTROL); + + /* + * CLR_INT clears the interrupt only if there's no error + * CLR_ERR clear the interrupt and the error register if there + * is an error + */ + cmd = readl(rngc->base + RNGC_COMMAND); + cmd |= RNGC_CMD_CLR_INT | RNGC_CMD_CLR_ERR; + writel(cmd, rngc->base + RNGC_COMMAND); +} + +static inline void imx_rngc_irq_unmask(struct imx_rngc *rngc) +{ + u32 ctrl; + + ctrl = readl(rngc->base + RNGC_CONTROL); + ctrl &= ~(RNGC_CTRL_MASK_DONE | RNGC_CTRL_MASK_ERROR); + writel(ctrl, rngc->base + RNGC_CONTROL); +} + +static int imx_rngc_self_test(struct imx_rngc *rngc) +{ + u32 cmd; + int ret; + + imx_rngc_irq_unmask(rngc); + + /* run self test */ + cmd = readl(rngc->base + RNGC_COMMAND); + writel(cmd | RNGC_CMD_SELF_TEST, rngc->base + RNGC_COMMAND); + + ret = wait_for_completion_timeout(&rngc->rng_op_done, msecs_to_jiffies(RNGC_TIMEOUT)); + imx_rngc_irq_mask_clear(rngc); + if (!ret) + return -ETIMEDOUT; + + return rngc->err_reg ? -EIO : 0; +} + +static int imx_rngc_read(struct hwrng *rng, void *data, size_t max, bool wait) +{ + struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng); + unsigned int status; + unsigned int level; + int retval = 0; + + while (max >= sizeof(u32)) { + status = readl(rngc->base + RNGC_STATUS); + + /* is there some error while reading this random number? */ + if (status & RNGC_STATUS_ERROR) + break; + + /* how many random numbers are in FIFO? [0-16] */ + level = (status & RNGC_STATUS_FIFO_LEVEL_MASK) >> + RNGC_STATUS_FIFO_LEVEL_SHIFT; + + if (level) { + /* retrieve a random number from FIFO */ + *(u32 *)data = readl(rngc->base + RNGC_FIFO); + + retval += sizeof(u32); + data += sizeof(u32); + max -= sizeof(u32); + } + } + + return retval ? retval : -EIO; +} + +static irqreturn_t imx_rngc_irq(int irq, void *priv) +{ + struct imx_rngc *rngc = (struct imx_rngc *)priv; + u32 status; + + /* + * clearing the interrupt will also clear the error register + * read error and status before clearing + */ + status = readl(rngc->base + RNGC_STATUS); + rngc->err_reg = readl(rngc->base + RNGC_ERROR); + + imx_rngc_irq_mask_clear(rngc); + + if (status & (RNGC_STATUS_SEED_DONE | RNGC_STATUS_ST_DONE)) + complete(&rngc->rng_op_done); + + return IRQ_HANDLED; +} + +static int imx_rngc_init(struct hwrng *rng) +{ + struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng); + u32 cmd, ctrl; + int ret; + + /* clear error */ + cmd = readl(rngc->base + RNGC_COMMAND); + writel(cmd | RNGC_CMD_CLR_ERR, rngc->base + RNGC_COMMAND); + + imx_rngc_irq_unmask(rngc); + + /* create seed, repeat while there is some statistical error */ + do { + /* seed creation */ + cmd = readl(rngc->base + RNGC_COMMAND); + writel(cmd | RNGC_CMD_SEED, rngc->base + RNGC_COMMAND); + + ret = wait_for_completion_timeout(&rngc->rng_op_done, msecs_to_jiffies(RNGC_TIMEOUT)); + if (!ret) { + ret = -ETIMEDOUT; + goto err; + } + + } while (rngc->err_reg == RNGC_ERROR_STATUS_STAT_ERR); + + if (rngc->err_reg) { + ret = -EIO; + goto err; + } + + /* + * enable automatic seeding, the rngc creates a new seed automatically + * after serving 2^20 random 160-bit words + */ + ctrl = readl(rngc->base + RNGC_CONTROL); + ctrl |= RNGC_CTRL_AUTO_SEED; + writel(ctrl, rngc->base + RNGC_CONTROL); + + /* + * if initialisation was successful, we keep the interrupt + * unmasked until imx_rngc_cleanup is called + * we mask the interrupt ourselves if we return an error + */ + return 0; + +err: + imx_rngc_irq_mask_clear(rngc); + return ret; +} + +static void imx_rngc_cleanup(struct hwrng *rng) +{ + struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng); + + imx_rngc_irq_mask_clear(rngc); +} + +static int imx_rngc_probe(struct platform_device *pdev) +{ + struct imx_rngc *rngc; + int ret; + int irq; + u32 ver_id; + u8 rng_type; + + rngc = devm_kzalloc(&pdev->dev, sizeof(*rngc), GFP_KERNEL); + if (!rngc) + return -ENOMEM; + + rngc->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(rngc->base)) + return PTR_ERR(rngc->base); + + rngc->clk = devm_clk_get_enabled(&pdev->dev, NULL); + if (IS_ERR(rngc->clk)) { + dev_err(&pdev->dev, "Can not get rng_clk\n"); + return PTR_ERR(rngc->clk); + } + + irq = platform_get_irq(pdev, 0); + if (irq < 0) + return irq; + + ver_id = readl(rngc->base + RNGC_VER_ID); + rng_type = ver_id >> RNGC_TYPE_SHIFT; + /* + * This driver supports only RNGC and RNGB. (There's a different + * driver for RNGA.) + */ + if (rng_type != RNGC_TYPE_RNGC && rng_type != RNGC_TYPE_RNGB) + return -ENODEV; + + init_completion(&rngc->rng_op_done); + + rngc->rng.name = pdev->name; + rngc->rng.init = imx_rngc_init; + rngc->rng.read = imx_rngc_read; + rngc->rng.cleanup = imx_rngc_cleanup; + rngc->rng.quality = 19; + + rngc->dev = &pdev->dev; + platform_set_drvdata(pdev, rngc); + + imx_rngc_irq_mask_clear(rngc); + + ret = devm_request_irq(&pdev->dev, + irq, imx_rngc_irq, 0, pdev->name, (void *)rngc); + if (ret) { + dev_err(rngc->dev, "Can't get interrupt working.\n"); + return ret; + } + + if (self_test) { + ret = imx_rngc_self_test(rngc); + if (ret) { + dev_err(rngc->dev, "self test failed\n"); + return ret; + } + } + + ret = devm_hwrng_register(&pdev->dev, &rngc->rng); + if (ret) { + dev_err(&pdev->dev, "hwrng registration failed\n"); + return ret; + } + + dev_info(&pdev->dev, + "Freescale RNG%c registered (HW revision %d.%02d)\n", + rng_type == RNGC_TYPE_RNGB ? 'B' : 'C', + (ver_id >> RNGC_VER_MAJ_SHIFT) & 0xff, ver_id & 0xff); + return 0; +} + +static int __maybe_unused imx_rngc_suspend(struct device *dev) +{ + struct imx_rngc *rngc = dev_get_drvdata(dev); + + clk_disable_unprepare(rngc->clk); + + return 0; +} + +static int __maybe_unused imx_rngc_resume(struct device *dev) +{ + struct imx_rngc *rngc = dev_get_drvdata(dev); + + clk_prepare_enable(rngc->clk); + + return 0; +} + +static SIMPLE_DEV_PM_OPS(imx_rngc_pm_ops, imx_rngc_suspend, imx_rngc_resume); + +static const struct of_device_id imx_rngc_dt_ids[] = { + { .compatible = "fsl,imx25-rngb", .data = NULL, }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, imx_rngc_dt_ids); + +static struct platform_driver imx_rngc_driver = { + .driver = { + .name = KBUILD_MODNAME, + .pm = &imx_rngc_pm_ops, + .of_match_table = imx_rngc_dt_ids, + }, +}; + +module_platform_driver_probe(imx_rngc_driver, imx_rngc_probe); + +MODULE_AUTHOR("Freescale Semiconductor, Inc."); +MODULE_DESCRIPTION("H/W RNGC driver for i.MX"); +MODULE_LICENSE("GPL"); |