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14#include <linux/clk.h>
15#include <linux/err.h>
16#include <linux/hw_random.h>
17#include <linux/io.h>
18#include <linux/module.h>
19#include <linux/of.h>
20#include <linux/platform_device.h>
21
22
23#define PRNG_DATA_OUT 0x0000
24#define PRNG_STATUS 0x0004
25#define PRNG_LFSR_CFG 0x0100
26#define PRNG_CONFIG 0x0104
27
28
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)
33
34#define MAX_HW_FIFO_DEPTH 16
35#define MAX_HW_FIFO_SIZE (MAX_HW_FIFO_DEPTH * 4)
36#define WORD_SZ 4
37
38struct msm_rng {
39 void __iomem *base;
40 struct clk *clk;
41 struct hwrng hwrng;
42};
43
44#define to_msm_rng(p) container_of(p, struct msm_rng, hwrng)
45
46static int msm_rng_enable(struct hwrng *hwrng, int enable)
47{
48 struct msm_rng *rng = to_msm_rng(hwrng);
49 u32 val;
50 int ret;
51
52 ret = clk_prepare_enable(rng->clk);
53 if (ret)
54 return ret;
55
56 if (enable) {
57
58 val = readl_relaxed(rng->base + PRNG_CONFIG);
59 if (val & PRNG_CONFIG_HW_ENABLE)
60 goto already_enabled;
61
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);
66
67 val = readl_relaxed(rng->base + PRNG_CONFIG);
68 val |= PRNG_CONFIG_HW_ENABLE;
69 writel(val, rng->base + PRNG_CONFIG);
70 } else {
71 val = readl_relaxed(rng->base + PRNG_CONFIG);
72 val &= ~PRNG_CONFIG_HW_ENABLE;
73 writel(val, rng->base + PRNG_CONFIG);
74 }
75
76already_enabled:
77 clk_disable_unprepare(rng->clk);
78 return 0;
79}
80
81static int msm_rng_read(struct hwrng *hwrng, void *data, size_t max, bool wait)
82{
83 struct msm_rng *rng = to_msm_rng(hwrng);
84 size_t currsize = 0;
85 u32 *retdata = data;
86 size_t maxsize;
87 int ret;
88 u32 val;
89
90
91 maxsize = min_t(size_t, MAX_HW_FIFO_SIZE, max);
92
93
94 if (maxsize < WORD_SZ)
95 return 0;
96
97 ret = clk_prepare_enable(rng->clk);
98 if (ret)
99 return ret;
100
101
102 do {
103 val = readl_relaxed(rng->base + PRNG_STATUS);
104 if (!(val & PRNG_STATUS_DATA_AVAIL))
105 break;
106
107 val = readl_relaxed(rng->base + PRNG_DATA_OUT);
108 if (!val)
109 break;
110
111 *retdata++ = val;
112 currsize += WORD_SZ;
113
114
115 if ((maxsize - currsize) < WORD_SZ)
116 break;
117 } while (currsize < maxsize);
118
119 clk_disable_unprepare(rng->clk);
120
121 return currsize;
122}
123
124static int msm_rng_init(struct hwrng *hwrng)
125{
126 return msm_rng_enable(hwrng, 1);
127}
128
129static void msm_rng_cleanup(struct hwrng *hwrng)
130{
131 msm_rng_enable(hwrng, 0);
132}
133
134static int msm_rng_probe(struct platform_device *pdev)
135{
136 struct resource *res;
137 struct msm_rng *rng;
138 int ret;
139
140 rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
141 if (!rng)
142 return -ENOMEM;
143
144 platform_set_drvdata(pdev, rng);
145
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);
150
151 rng->clk = devm_clk_get(&pdev->dev, "core");
152 if (IS_ERR(rng->clk))
153 return PTR_ERR(rng->clk);
154
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,
159
160 ret = hwrng_register(&rng->hwrng);
161 if (ret) {
162 dev_err(&pdev->dev, "failed to register hwrng\n");
163 return ret;
164 }
165
166 return 0;
167}
168
169static int msm_rng_remove(struct platform_device *pdev)
170{
171 struct msm_rng *rng = platform_get_drvdata(pdev);
172
173 hwrng_unregister(&rng->hwrng);
174 return 0;
175}
176
177static const struct of_device_id msm_rng_of_match[] = {
178 { .compatible = "qcom,prng", },
179 {}
180};
181MODULE_DEVICE_TABLE(of, msm_rng_of_match);
182
183static struct platform_driver msm_rng_driver = {
184 .probe = msm_rng_probe,
185 .remove = msm_rng_remove,
186 .driver = {
187 .name = KBUILD_MODNAME,
188 .of_match_table = of_match_ptr(msm_rng_of_match),
189 }
190};
191module_platform_driver(msm_rng_driver);
192
193MODULE_ALIAS("platform:" KBUILD_MODNAME);
194MODULE_AUTHOR("The Linux Foundation");
195MODULE_DESCRIPTION("Qualcomm MSM random number generator driver");
196MODULE_LICENSE("GPL v2");
197
