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157 lines
4.0 KiB
157 lines
4.0 KiB
/* |
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* RNG driver for TX4939 Random Number Generators (RNG) |
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* |
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* Copyright (C) 2009 Atsushi Nemoto <[email protected]> |
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* |
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* This file is subject to the terms and conditions of the GNU General Public |
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* License. See the file "COPYING" in the main directory of this archive |
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* for more details. |
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*/ |
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#include <linux/err.h> |
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#include <linux/module.h> |
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#include <linux/kernel.h> |
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#include <linux/init.h> |
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#include <linux/delay.h> |
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#include <linux/io.h> |
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#include <linux/platform_device.h> |
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#include <linux/hw_random.h> |
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#include <linux/gfp.h> |
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#define TX4939_RNG_RCSR 0x00000000 |
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#define TX4939_RNG_ROR(n) (0x00000018 + (n) * 8) |
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#define TX4939_RNG_RCSR_INTE 0x00000008 |
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#define TX4939_RNG_RCSR_RST 0x00000004 |
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#define TX4939_RNG_RCSR_FIN 0x00000002 |
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#define TX4939_RNG_RCSR_ST 0x00000001 |
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struct tx4939_rng { |
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struct hwrng rng; |
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void __iomem *base; |
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u64 databuf[3]; |
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unsigned int data_avail; |
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}; |
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static void rng_io_start(void) |
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{ |
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#ifndef CONFIG_64BIT |
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/* |
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* readq is reading a 64-bit register using a 64-bit load. On |
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* a 32-bit kernel however interrupts or any other processor |
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* exception would clobber the upper 32-bit of the processor |
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* register so interrupts need to be disabled. |
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*/ |
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local_irq_disable(); |
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#endif |
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} |
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static void rng_io_end(void) |
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{ |
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#ifndef CONFIG_64BIT |
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local_irq_enable(); |
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#endif |
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} |
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static u64 read_rng(void __iomem *base, unsigned int offset) |
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{ |
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return ____raw_readq(base + offset); |
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} |
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static void write_rng(u64 val, void __iomem *base, unsigned int offset) |
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{ |
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return ____raw_writeq(val, base + offset); |
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} |
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static int tx4939_rng_data_present(struct hwrng *rng, int wait) |
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{ |
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struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng); |
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int i; |
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if (rngdev->data_avail) |
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return rngdev->data_avail; |
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for (i = 0; i < 20; i++) { |
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rng_io_start(); |
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if (!(read_rng(rngdev->base, TX4939_RNG_RCSR) |
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& TX4939_RNG_RCSR_ST)) { |
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rngdev->databuf[0] = |
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read_rng(rngdev->base, TX4939_RNG_ROR(0)); |
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rngdev->databuf[1] = |
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read_rng(rngdev->base, TX4939_RNG_ROR(1)); |
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rngdev->databuf[2] = |
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read_rng(rngdev->base, TX4939_RNG_ROR(2)); |
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rngdev->data_avail = |
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sizeof(rngdev->databuf) / sizeof(u32); |
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/* Start RNG */ |
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write_rng(TX4939_RNG_RCSR_ST, |
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rngdev->base, TX4939_RNG_RCSR); |
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wait = 0; |
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} |
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rng_io_end(); |
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if (!wait) |
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break; |
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/* 90 bus clock cycles by default for generation */ |
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ndelay(90 * 5); |
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} |
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return rngdev->data_avail; |
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} |
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static int tx4939_rng_data_read(struct hwrng *rng, u32 *buffer) |
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{ |
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struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng); |
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rngdev->data_avail--; |
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*buffer = *((u32 *)&rngdev->databuf + rngdev->data_avail); |
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return sizeof(u32); |
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} |
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static int __init tx4939_rng_probe(struct platform_device *dev) |
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{ |
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struct tx4939_rng *rngdev; |
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int i; |
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rngdev = devm_kzalloc(&dev->dev, sizeof(*rngdev), GFP_KERNEL); |
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if (!rngdev) |
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return -ENOMEM; |
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rngdev->base = devm_platform_ioremap_resource(dev, 0); |
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if (IS_ERR(rngdev->base)) |
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return PTR_ERR(rngdev->base); |
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rngdev->rng.name = dev_name(&dev->dev); |
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rngdev->rng.data_present = tx4939_rng_data_present; |
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rngdev->rng.data_read = tx4939_rng_data_read; |
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rng_io_start(); |
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/* Reset RNG */ |
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write_rng(TX4939_RNG_RCSR_RST, rngdev->base, TX4939_RNG_RCSR); |
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write_rng(0, rngdev->base, TX4939_RNG_RCSR); |
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/* Start RNG */ |
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write_rng(TX4939_RNG_RCSR_ST, rngdev->base, TX4939_RNG_RCSR); |
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rng_io_end(); |
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/* |
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* Drop first two results. From the datasheet: |
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* The quality of the random numbers generated immediately |
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* after reset can be insufficient. Therefore, do not use |
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* random numbers obtained from the first and second |
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* generations; use the ones from the third or subsequent |
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* generation. |
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*/ |
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for (i = 0; i < 2; i++) { |
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rngdev->data_avail = 0; |
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if (!tx4939_rng_data_present(&rngdev->rng, 1)) |
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return -EIO; |
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} |
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platform_set_drvdata(dev, rngdev); |
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return devm_hwrng_register(&dev->dev, &rngdev->rng); |
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} |
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static struct platform_driver tx4939_rng_driver = { |
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.driver = { |
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.name = "tx4939-rng", |
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}, |
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}; |
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module_platform_driver_probe(tx4939_rng_driver, tx4939_rng_probe); |
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MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver for TX4939"); |
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MODULE_LICENSE("GPL");
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