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path: root/drivers/char/hw_random/mxc-rnga.c
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Diffstat (limited to 'drivers/char/hw_random/mxc-rnga.c')
-rw-r--r--drivers/char/hw_random/mxc-rnga.c209
1 files changed, 209 insertions, 0 deletions
diff --git a/drivers/char/hw_random/mxc-rnga.c b/drivers/char/hw_random/mxc-rnga.c
new file mode 100644
index 0000000000..008763c988
--- /dev/null
+++ b/drivers/char/hw_random/mxc-rnga.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * RNG driver for Freescale RNGA
+ *
+ * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Author: Alan Carvalho de Assis <acassis@gmail.com>
+ */
+
+/*
+ *
+ * This driver is based on other RNG drivers.
+ */
+
+#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>
+
+/* RNGA Registers */
+#define RNGA_CONTROL 0x00
+#define RNGA_STATUS 0x04
+#define RNGA_ENTROPY 0x08
+#define RNGA_OUTPUT_FIFO 0x0c
+#define RNGA_MODE 0x10
+#define RNGA_VERIFICATION_CONTROL 0x14
+#define RNGA_OSC_CONTROL_COUNTER 0x18
+#define RNGA_OSC1_COUNTER 0x1c
+#define RNGA_OSC2_COUNTER 0x20
+#define RNGA_OSC_COUNTER_STATUS 0x24
+
+/* RNGA Registers Range */
+#define RNG_ADDR_RANGE 0x28
+
+/* RNGA Control Register */
+#define RNGA_CONTROL_SLEEP 0x00000010
+#define RNGA_CONTROL_CLEAR_INT 0x00000008
+#define RNGA_CONTROL_MASK_INTS 0x00000004
+#define RNGA_CONTROL_HIGH_ASSURANCE 0x00000002
+#define RNGA_CONTROL_GO 0x00000001
+
+#define RNGA_STATUS_LEVEL_MASK 0x0000ff00
+
+/* RNGA Status Register */
+#define RNGA_STATUS_OSC_DEAD 0x80000000
+#define RNGA_STATUS_SLEEP 0x00000010
+#define RNGA_STATUS_ERROR_INT 0x00000008
+#define RNGA_STATUS_FIFO_UNDERFLOW 0x00000004
+#define RNGA_STATUS_LAST_READ_STATUS 0x00000002
+#define RNGA_STATUS_SECURITY_VIOLATION 0x00000001
+
+struct mxc_rng {
+ struct device *dev;
+ struct hwrng rng;
+ void __iomem *mem;
+ struct clk *clk;
+};
+
+static int mxc_rnga_data_present(struct hwrng *rng, int wait)
+{
+ int i;
+ struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
+
+ for (i = 0; i < 20; i++) {
+ /* how many random numbers are in FIFO? [0-16] */
+ int level = (__raw_readl(mxc_rng->mem + RNGA_STATUS) &
+ RNGA_STATUS_LEVEL_MASK) >> 8;
+ if (level || !wait)
+ return !!level;
+ udelay(10);
+ }
+ return 0;
+}
+
+static int mxc_rnga_data_read(struct hwrng *rng, u32 * data)
+{
+ int err;
+ u32 ctrl;
+ struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
+
+ /* retrieve a random number from FIFO */
+ *data = __raw_readl(mxc_rng->mem + RNGA_OUTPUT_FIFO);
+
+ /* some error while reading this random number? */
+ err = __raw_readl(mxc_rng->mem + RNGA_STATUS) & RNGA_STATUS_ERROR_INT;
+
+ /* if error: clear error interrupt, but doesn't return random number */
+ if (err) {
+ dev_dbg(mxc_rng->dev, "Error while reading random number!\n");
+ ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
+ __raw_writel(ctrl | RNGA_CONTROL_CLEAR_INT,
+ mxc_rng->mem + RNGA_CONTROL);
+ return 0;
+ } else
+ return 4;
+}
+
+static int mxc_rnga_init(struct hwrng *rng)
+{
+ u32 ctrl, osc;
+ struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
+
+ /* wake up */
+ ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
+ __raw_writel(ctrl & ~RNGA_CONTROL_SLEEP, mxc_rng->mem + RNGA_CONTROL);
+
+ /* verify if oscillator is working */
+ osc = __raw_readl(mxc_rng->mem + RNGA_STATUS);
+ if (osc & RNGA_STATUS_OSC_DEAD) {
+ dev_err(mxc_rng->dev, "RNGA Oscillator is dead!\n");
+ return -ENODEV;
+ }
+
+ /* go running */
+ ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
+ __raw_writel(ctrl | RNGA_CONTROL_GO, mxc_rng->mem + RNGA_CONTROL);
+
+ return 0;
+}
+
+static void mxc_rnga_cleanup(struct hwrng *rng)
+{
+ u32 ctrl;
+ struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
+
+ ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
+
+ /* stop rnga */
+ __raw_writel(ctrl & ~RNGA_CONTROL_GO, mxc_rng->mem + RNGA_CONTROL);
+}
+
+static int __init mxc_rnga_probe(struct platform_device *pdev)
+{
+ int err;
+ struct mxc_rng *mxc_rng;
+
+ mxc_rng = devm_kzalloc(&pdev->dev, sizeof(*mxc_rng), GFP_KERNEL);
+ if (!mxc_rng)
+ return -ENOMEM;
+
+ mxc_rng->dev = &pdev->dev;
+ mxc_rng->rng.name = "mxc-rnga";
+ mxc_rng->rng.init = mxc_rnga_init;
+ mxc_rng->rng.cleanup = mxc_rnga_cleanup;
+ mxc_rng->rng.data_present = mxc_rnga_data_present;
+ mxc_rng->rng.data_read = mxc_rnga_data_read;
+
+ mxc_rng->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(mxc_rng->clk)) {
+ dev_err(&pdev->dev, "Could not get rng_clk!\n");
+ return PTR_ERR(mxc_rng->clk);
+ }
+
+ err = clk_prepare_enable(mxc_rng->clk);
+ if (err)
+ return err;
+
+ mxc_rng->mem = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(mxc_rng->mem)) {
+ err = PTR_ERR(mxc_rng->mem);
+ goto err_ioremap;
+ }
+
+ err = hwrng_register(&mxc_rng->rng);
+ if (err) {
+ dev_err(&pdev->dev, "MXC RNGA registering failed (%d)\n", err);
+ goto err_ioremap;
+ }
+
+ return 0;
+
+err_ioremap:
+ clk_disable_unprepare(mxc_rng->clk);
+ return err;
+}
+
+static int __exit mxc_rnga_remove(struct platform_device *pdev)
+{
+ struct mxc_rng *mxc_rng = platform_get_drvdata(pdev);
+
+ hwrng_unregister(&mxc_rng->rng);
+
+ clk_disable_unprepare(mxc_rng->clk);
+
+ return 0;
+}
+
+static const struct of_device_id mxc_rnga_of_match[] = {
+ { .compatible = "fsl,imx21-rnga", },
+ { .compatible = "fsl,imx31-rnga", },
+ { /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, mxc_rnga_of_match);
+
+static struct platform_driver mxc_rnga_driver = {
+ .driver = {
+ .name = "mxc_rnga",
+ .of_match_table = mxc_rnga_of_match,
+ },
+ .remove = __exit_p(mxc_rnga_remove),
+};
+
+module_platform_driver_probe(mxc_rnga_driver, mxc_rnga_probe);
+
+MODULE_AUTHOR("Freescale Semiconductor, Inc.");
+MODULE_DESCRIPTION("H/W RNGA driver for i.MX");
+MODULE_LICENSE("GPL");