MIPS: hwrng: Add TX4939 RNG driver
This patch adds support for the integrated RNG of the TX4939 SoC.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/drivers/char/hw_random/tx4939-rng.c b/drivers/char/hw_random/tx4939-rng.c
new file mode 100644
index 0000000..544d9085
--- /dev/null
+++ b/drivers/char/hw_random/tx4939-rng.c
@@ -0,0 +1,184 @@
+/*
+ * RNG driver for TX4939 Random Number Generators (RNG)
+ *
+ * Copyright (C) 2009 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/hw_random.h>
+
+#define TX4939_RNG_RCSR 0x00000000
+#define TX4939_RNG_ROR(n) (0x00000018 + (n) * 8)
+
+#define TX4939_RNG_RCSR_INTE 0x00000008
+#define TX4939_RNG_RCSR_RST 0x00000004
+#define TX4939_RNG_RCSR_FIN 0x00000002
+#define TX4939_RNG_RCSR_ST 0x00000001
+
+struct tx4939_rng {
+ struct hwrng rng;
+ void __iomem *base;
+ u64 databuf[3];
+ unsigned int data_avail;
+};
+
+static void rng_io_start(void)
+{
+#ifndef CONFIG_64BIT
+ /*
+ * readq is reading a 64-bit register using a 64-bit load. On
+ * a 32-bit kernel however interrupts or any other processor
+ * exception would clobber the upper 32-bit of the processor
+ * register so interrupts need to be disabled.
+ */
+ local_irq_disable();
+#endif
+}
+
+static void rng_io_end(void)
+{
+#ifndef CONFIG_64BIT
+ local_irq_enable();
+#endif
+}
+
+static u64 read_rng(void __iomem *base, unsigned int offset)
+{
+ return ____raw_readq(base + offset);
+}
+
+static void write_rng(u64 val, void __iomem *base, unsigned int offset)
+{
+ return ____raw_writeq(val, base + offset);
+}
+
+static int tx4939_rng_data_present(struct hwrng *rng, int wait)
+{
+ struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng);
+ int i;
+
+ if (rngdev->data_avail)
+ return rngdev->data_avail;
+ for (i = 0; i < 20; i++) {
+ rng_io_start();
+ if (!(read_rng(rngdev->base, TX4939_RNG_RCSR)
+ & TX4939_RNG_RCSR_ST)) {
+ rngdev->databuf[0] =
+ read_rng(rngdev->base, TX4939_RNG_ROR(0));
+ rngdev->databuf[1] =
+ read_rng(rngdev->base, TX4939_RNG_ROR(1));
+ rngdev->databuf[2] =
+ read_rng(rngdev->base, TX4939_RNG_ROR(2));
+ rngdev->data_avail =
+ sizeof(rngdev->databuf) / sizeof(u32);
+ /* Start RNG */
+ write_rng(TX4939_RNG_RCSR_ST,
+ rngdev->base, TX4939_RNG_RCSR);
+ wait = 0;
+ }
+ rng_io_end();
+ if (!wait)
+ break;
+ /* 90 bus clock cycles by default for generation */
+ ndelay(90 * 5);
+ }
+ return rngdev->data_avail;
+}
+
+static int tx4939_rng_data_read(struct hwrng *rng, u32 *buffer)
+{
+ struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng);
+
+ rngdev->data_avail--;
+ *buffer = *((u32 *)&rngdev->databuf + rngdev->data_avail);
+ return sizeof(u32);
+}
+
+static int __init tx4939_rng_probe(struct platform_device *dev)
+{
+ struct tx4939_rng *rngdev;
+ struct resource *r;
+ int i;
+
+ r = platform_get_resource(dev, IORESOURCE_MEM, 0);
+ if (!r)
+ return -EBUSY;
+ rngdev = devm_kzalloc(&dev->dev, sizeof(*rngdev), GFP_KERNEL);
+ if (!rngdev)
+ return -ENOMEM;
+ if (!devm_request_mem_region(&dev->dev, r->start, resource_size(r),
+ dev_name(&dev->dev)))
+ return -EBUSY;
+ rngdev->base = devm_ioremap(&dev->dev, r->start, resource_size(r));
+ if (!rngdev->base)
+ return -EBUSY;
+
+ rngdev->rng.name = dev_name(&dev->dev);
+ rngdev->rng.data_present = tx4939_rng_data_present;
+ rngdev->rng.data_read = tx4939_rng_data_read;
+
+ rng_io_start();
+ /* Reset RNG */
+ write_rng(TX4939_RNG_RCSR_RST, rngdev->base, TX4939_RNG_RCSR);
+ write_rng(0, rngdev->base, TX4939_RNG_RCSR);
+ /* Start RNG */
+ write_rng(TX4939_RNG_RCSR_ST, rngdev->base, TX4939_RNG_RCSR);
+ rng_io_end();
+ /*
+ * Drop first two results. From the datasheet:
+ * The quality of the random numbers generated immediately
+ * after reset can be insufficient. Therefore, do not use
+ * random numbers obtained from the first and second
+ * generations; use the ones from the third or subsequent
+ * generation.
+ */
+ for (i = 0; i < 2; i++) {
+ rngdev->data_avail = 0;
+ if (!tx4939_rng_data_present(&rngdev->rng, 1))
+ return -EIO;
+ }
+
+ platform_set_drvdata(dev, rngdev);
+ return hwrng_register(&rngdev->rng);
+}
+
+static int __exit tx4939_rng_remove(struct platform_device *dev)
+{
+ struct tx4939_rng *rngdev = platform_get_drvdata(dev);
+
+ hwrng_unregister(&rngdev->rng);
+ platform_set_drvdata(dev, NULL);
+ return 0;
+}
+
+static struct platform_driver tx4939_rng_driver = {
+ .driver = {
+ .name = "tx4939-rng",
+ .owner = THIS_MODULE,
+ },
+ .remove = tx4939_rng_remove,
+};
+
+static int __init tx4939rng_init(void)
+{
+ return platform_driver_probe(&tx4939_rng_driver, tx4939_rng_probe);
+}
+
+static void __exit tx4939rng_exit(void)
+{
+ platform_driver_unregister(&tx4939_rng_driver);
+}
+
+module_init(tx4939rng_init);
+module_exit(tx4939rng_exit);
+
+MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver for TX4939");
+MODULE_LICENSE("GPL");