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path: root/drivers/char/hw_random/pasemi-rng.c
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-rw-r--r--drivers/char/hw_random/pasemi-rng.c119
1 files changed, 119 insertions, 0 deletions
diff --git a/drivers/char/hw_random/pasemi-rng.c b/drivers/char/hw_random/pasemi-rng.c
new file mode 100644
index 000000000..2498d4ef9
--- /dev/null
+++ b/drivers/char/hw_random/pasemi-rng.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2006-2007 PA Semi, Inc
+ *
+ * Maintained by: Olof Johansson <olof@lixom.net>
+ *
+ * Driver for the PWRficient onchip rng
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/hw_random.h>
+#include <linux/delay.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/io.h>
+
+#define SDCRNG_CTL_REG 0x00
+#define SDCRNG_CTL_FVLD_M 0x0000f000
+#define SDCRNG_CTL_FVLD_S 12
+#define SDCRNG_CTL_KSZ 0x00000800
+#define SDCRNG_CTL_RSRC_CRG 0x00000010
+#define SDCRNG_CTL_RSRC_RRG 0x00000000
+#define SDCRNG_CTL_CE 0x00000004
+#define SDCRNG_CTL_RE 0x00000002
+#define SDCRNG_CTL_DR 0x00000001
+#define SDCRNG_CTL_SELECT_RRG_RNG (SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG)
+#define SDCRNG_CTL_SELECT_CRG_RNG (SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG)
+#define SDCRNG_VAL_REG 0x20
+
+#define MODULE_NAME "pasemi_rng"
+
+static int pasemi_rng_data_present(struct hwrng *rng, int wait)
+{
+ void __iomem *rng_regs = (void __iomem *)rng->priv;
+ int data, i;
+
+ for (i = 0; i < 20; i++) {
+ data = (in_le32(rng_regs + SDCRNG_CTL_REG)
+ & SDCRNG_CTL_FVLD_M) ? 1 : 0;
+ if (data || !wait)
+ break;
+ udelay(10);
+ }
+ return data;
+}
+
+static int pasemi_rng_data_read(struct hwrng *rng, u32 *data)
+{
+ void __iomem *rng_regs = (void __iomem *)rng->priv;
+ *data = in_le32(rng_regs + SDCRNG_VAL_REG);
+ return 4;
+}
+
+static int pasemi_rng_init(struct hwrng *rng)
+{
+ void __iomem *rng_regs = (void __iomem *)rng->priv;
+ u32 ctl;
+
+ ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ;
+ out_le32(rng_regs + SDCRNG_CTL_REG, ctl);
+ out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR);
+
+ return 0;
+}
+
+static void pasemi_rng_cleanup(struct hwrng *rng)
+{
+ void __iomem *rng_regs = (void __iomem *)rng->priv;
+ u32 ctl;
+
+ ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE;
+ out_le32(rng_regs + SDCRNG_CTL_REG,
+ in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl);
+}
+
+static struct hwrng pasemi_rng = {
+ .name = MODULE_NAME,
+ .init = pasemi_rng_init,
+ .cleanup = pasemi_rng_cleanup,
+ .data_present = pasemi_rng_data_present,
+ .data_read = pasemi_rng_data_read,
+};
+
+static int rng_probe(struct platform_device *pdev)
+{
+ void __iomem *rng_regs;
+
+ rng_regs = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(rng_regs))
+ return PTR_ERR(rng_regs);
+
+ pasemi_rng.priv = (unsigned long)rng_regs;
+
+ pr_info("Registering PA Semi RNG\n");
+ return devm_hwrng_register(&pdev->dev, &pasemi_rng);
+}
+
+static const struct of_device_id rng_match[] = {
+ { .compatible = "1682m-rng", },
+ { .compatible = "pasemi,pwrficient-rng", },
+ { },
+};
+MODULE_DEVICE_TABLE(of, rng_match);
+
+static struct platform_driver rng_driver = {
+ .driver = {
+ .name = "pasemi-rng",
+ .of_match_table = rng_match,
+ },
+ .probe = rng_probe,
+};
+
+module_platform_driver(rng_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>");
+MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor");