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/Kconfig b/drivers/char/hw_random/Kconfig
index f4b3f72..ce66a70 100644 (file)
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -149,6 +149,19 @@ config HW_RANDOM_VIRTIO
          To compile this driver as a module, choose M here: the
          module will be called virtio-rng.  If unsure, say N.
 
+config HW_RANDOM_TX4939
+       tristate "TX4939 Random Number Generator support"
+       depends on HW_RANDOM && SOC_TX4939
+       default HW_RANDOM
+       ---help---
+         This driver provides kernel-side support for the Random Number
+         Generator hardware found on TX4939 SoC.
+
+         To compile this driver as a module, choose M here: the
+         module will be called tx4939-rng.
+
+         If unsure, say Y.
+
 config HW_RANDOM_MXC_RNGA
        tristate "Freescale i.MX RNGA Random Number Generator"
        depends on HW_RANDOM && ARCH_HAS_RNGA

diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index fd1ecd2..676828b 100644 (file)
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -15,4 +15,5 @@ obj-$(CONFIG_HW_RANDOM_IXP4XX) += ixp4xx-rng.o
 obj-$(CONFIG_HW_RANDOM_OMAP) += omap-rng.o
 obj-$(CONFIG_HW_RANDOM_PASEMI) += pasemi-rng.o
 obj-$(CONFIG_HW_RANDOM_VIRTIO) += virtio-rng.o
+obj-$(CONFIG_HW_RANDOM_TX4939) += tx4939-rng.o
 obj-$(CONFIG_HW_RANDOM_MXC_RNGA) += mxc-rnga.o

diff --git a/drivers/char/hw_random/tx4939-rng.c b/drivers/char/hw_random/tx4939-rng.c
new file mode 100644 (file)
index 0000000..544d908
--- /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");