2 * Copyright (c) 2011-2013, The Linux Foundation. All rights reserved.
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 and
6 * only version 2 as published by the Free Software Foundation.
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
14 #include <linux/clk.h>
15 #include <linux/err.h>
16 #include <linux/hw_random.h>
18 #include <linux/module.h>
20 #include <linux/platform_device.h>
22 /* Device specific register offsets */
23 #define PRNG_DATA_OUT 0x0000
24 #define PRNG_STATUS 0x0004
25 #define PRNG_LFSR_CFG 0x0100
26 #define PRNG_CONFIG 0x0104
28 /* Device specific register masks and config values */
29 #define PRNG_LFSR_CFG_MASK 0x0000ffff
30 #define PRNG_LFSR_CFG_CLOCKS 0x0000dddd
31 #define PRNG_CONFIG_HW_ENABLE BIT(1)
32 #define PRNG_STATUS_DATA_AVAIL BIT(0)
34 #define MAX_HW_FIFO_DEPTH 16
35 #define MAX_HW_FIFO_SIZE (MAX_HW_FIFO_DEPTH * 4)
44 #define to_msm_rng(p) container_of(p, struct msm_rng, hwrng)
46 static int msm_rng_enable(struct hwrng
*hwrng
, int enable
)
48 struct msm_rng
*rng
= to_msm_rng(hwrng
);
52 ret
= clk_prepare_enable(rng
->clk
);
57 /* Enable PRNG only if it is not already enabled */
58 val
= readl_relaxed(rng
->base
+ PRNG_CONFIG
);
59 if (val
& PRNG_CONFIG_HW_ENABLE
)
62 val
= readl_relaxed(rng
->base
+ PRNG_LFSR_CFG
);
63 val
&= ~PRNG_LFSR_CFG_MASK
;
64 val
|= PRNG_LFSR_CFG_CLOCKS
;
65 writel(val
, rng
->base
+ PRNG_LFSR_CFG
);
67 val
= readl_relaxed(rng
->base
+ PRNG_CONFIG
);
68 val
|= PRNG_CONFIG_HW_ENABLE
;
69 writel(val
, rng
->base
+ PRNG_CONFIG
);
71 val
= readl_relaxed(rng
->base
+ PRNG_CONFIG
);
72 val
&= ~PRNG_CONFIG_HW_ENABLE
;
73 writel(val
, rng
->base
+ PRNG_CONFIG
);
77 clk_disable_unprepare(rng
->clk
);
81 static int msm_rng_read(struct hwrng
*hwrng
, void *data
, size_t max
, bool wait
)
83 struct msm_rng
*rng
= to_msm_rng(hwrng
);
90 /* calculate max size bytes to transfer back to caller */
91 maxsize
= min_t(size_t, MAX_HW_FIFO_SIZE
, max
);
93 /* no room for word data */
94 if (maxsize
< WORD_SZ
)
97 ret
= clk_prepare_enable(rng
->clk
);
101 /* read random data from hardware */
103 val
= readl_relaxed(rng
->base
+ PRNG_STATUS
);
104 if (!(val
& PRNG_STATUS_DATA_AVAIL
))
107 val
= readl_relaxed(rng
->base
+ PRNG_DATA_OUT
);
114 /* make sure we stay on 32bit boundary */
115 if ((maxsize
- currsize
) < WORD_SZ
)
117 } while (currsize
< maxsize
);
119 clk_disable_unprepare(rng
->clk
);
124 static int msm_rng_init(struct hwrng
*hwrng
)
126 return msm_rng_enable(hwrng
, 1);
129 static void msm_rng_cleanup(struct hwrng
*hwrng
)
131 msm_rng_enable(hwrng
, 0);
134 static int msm_rng_probe(struct platform_device
*pdev
)
136 struct resource
*res
;
140 rng
= devm_kzalloc(&pdev
->dev
, sizeof(*rng
), GFP_KERNEL
);
144 platform_set_drvdata(pdev
, rng
);
146 res
= platform_get_resource(pdev
, IORESOURCE_MEM
, 0);
147 rng
->base
= devm_ioremap_resource(&pdev
->dev
, res
);
148 if (IS_ERR(rng
->base
))
149 return PTR_ERR(rng
->base
);
151 rng
->clk
= devm_clk_get(&pdev
->dev
, "core");
152 if (IS_ERR(rng
->clk
))
153 return PTR_ERR(rng
->clk
);
155 rng
->hwrng
.name
= KBUILD_MODNAME
,
156 rng
->hwrng
.init
= msm_rng_init
,
157 rng
->hwrng
.cleanup
= msm_rng_cleanup
,
158 rng
->hwrng
.read
= msm_rng_read
,
160 ret
= hwrng_register(&rng
->hwrng
);
162 dev_err(&pdev
->dev
, "failed to register hwrng\n");
169 static int msm_rng_remove(struct platform_device
*pdev
)
171 struct msm_rng
*rng
= platform_get_drvdata(pdev
);
173 hwrng_unregister(&rng
->hwrng
);
177 static const struct of_device_id msm_rng_of_match
[] = {
178 { .compatible
= "qcom,prng", },
181 MODULE_DEVICE_TABLE(of
, msm_rng_of_match
);
183 static struct platform_driver msm_rng_driver
= {
184 .probe
= msm_rng_probe
,
185 .remove
= msm_rng_remove
,
187 .name
= KBUILD_MODNAME
,
188 .of_match_table
= of_match_ptr(msm_rng_of_match
),
191 module_platform_driver(msm_rng_driver
);
193 MODULE_ALIAS("platform:" KBUILD_MODNAME
);
194 MODULE_AUTHOR("The Linux Foundation");
195 MODULE_DESCRIPTION("Qualcomm MSM random number generator driver");
196 MODULE_LICENSE("GPL v2");