1 /*
2 * Random Number Generator driver for the Keystone SOC
3 *
4 * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com
5 *
6 * Authors: Sandeep Nair
7 * Vitaly Andrianov
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * version 2 as published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
17 */
18
19 #include <linux/hw_random.h>
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <linux/io.h>
23 #include <linux/platform_device.h>
24 #include <linux/clk.h>
25 #include <linux/pm_runtime.h>
26 #include <linux/err.h>
27 #include <linux/regmap.h>
28 #include <linux/mfd/syscon.h>
29 #include <linux/of.h>
30 #include <linux/of_address.h>
31 #include <linux/delay.h>
32
33 #define SA_CMD_STATUS_OFS 0x8
34
35 /* TRNG enable control in SA System module*/
36 #define SA_CMD_STATUS_REG_TRNG_ENABLE BIT(3)
37
38 /* TRNG start control in TRNG module */
39 #define TRNG_CNTL_REG_TRNG_ENABLE BIT(10)
40
41 /* Data ready indicator in STATUS register */
42 #define TRNG_STATUS_REG_READY BIT(0)
43
44 /* Data ready clear control in INTACK register */
45 #define TRNG_INTACK_REG_READY BIT(0)
46
47 /*
48 * Number of samples taken to gather entropy during startup.
49 * If value is 0, the number of samples is 2^24 else
50 * equals value times 2^8.
51 */
52 #define TRNG_DEF_STARTUP_CYCLES 0
53 #define TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT 16
54
55 /*
56 * Minimum number of samples taken to regenerate entropy
57 * If value is 0, the number of samples is 2^24 else
58 * equals value times 2^6.
59 */
60 #define TRNG_DEF_MIN_REFILL_CYCLES 1
61 #define TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT 0
62
63 /*
64 * Maximum number of samples taken to regenerate entropy
65 * If value is 0, the number of samples is 2^24 else
66 * equals value times 2^8.
67 */
68 #define TRNG_DEF_MAX_REFILL_CYCLES 0
69 #define TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT 16
70
71 /* Number of CLK input cycles between samples */
72 #define TRNG_DEF_CLK_DIV_CYCLES 0
73 #define TRNG_CFG_REG_SAMPLE_DIV_SHIFT 8
74
75 /* Maximum retries to get rng data */
76 #define SA_MAX_RNG_DATA_RETRIES 5
77 /* Delay between retries (in usecs) */
78 #define SA_RNG_DATA_RETRY_DELAY 5
79
80 struct trng_regs {
81 u32 output_l;
82 u32 output_h;
83 u32 status;
84 u32 intmask;
85 u32 intack;
86 u32 control;
87 u32 config;
88 };
89
90 struct ks_sa_rng {
91 struct device *dev;
92 struct hwrng rng;
93 struct clk *clk;
94 struct regmap *regmap_cfg;
95 struct trng_regs *reg_rng;
96 };
97
ks_sa_rng_init(struct hwrng * rng)98 static int ks_sa_rng_init(struct hwrng *rng)
99 {
100 u32 value;
101 struct device *dev = (struct device *)rng->priv;
102 struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
103
104 /* Enable RNG module */
105 regmap_write_bits(ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,
106 SA_CMD_STATUS_REG_TRNG_ENABLE,
107 SA_CMD_STATUS_REG_TRNG_ENABLE);
108
109 /* Configure RNG module */
110 writel(0, &ks_sa_rng->reg_rng->control);
111 value = TRNG_DEF_STARTUP_CYCLES << TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT;
112 writel(value, &ks_sa_rng->reg_rng->control);
113
114 value = (TRNG_DEF_MIN_REFILL_CYCLES <<
115 TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT) |
116 (TRNG_DEF_MAX_REFILL_CYCLES <<
117 TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT) |
118 (TRNG_DEF_CLK_DIV_CYCLES <<
119 TRNG_CFG_REG_SAMPLE_DIV_SHIFT);
120
121 writel(value, &ks_sa_rng->reg_rng->config);
122
123 /* Disable all interrupts from TRNG */
124 writel(0, &ks_sa_rng->reg_rng->intmask);
125
126 /* Enable RNG */
127 value = readl(&ks_sa_rng->reg_rng->control);
128 value |= TRNG_CNTL_REG_TRNG_ENABLE;
129 writel(value, &ks_sa_rng->reg_rng->control);
130
131 return 0;
132 }
133
ks_sa_rng_cleanup(struct hwrng * rng)134 static void ks_sa_rng_cleanup(struct hwrng *rng)
135 {
136 struct device *dev = (struct device *)rng->priv;
137 struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
138
139 /* Disable RNG */
140 writel(0, &ks_sa_rng->reg_rng->control);
141 regmap_write_bits(ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,
142 SA_CMD_STATUS_REG_TRNG_ENABLE, 0);
143 }
144
ks_sa_rng_data_read(struct hwrng * rng,u32 * data)145 static int ks_sa_rng_data_read(struct hwrng *rng, u32 *data)
146 {
147 struct device *dev = (struct device *)rng->priv;
148 struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
149
150 /* Read random data */
151 data[0] = readl(&ks_sa_rng->reg_rng->output_l);
152 data[1] = readl(&ks_sa_rng->reg_rng->output_h);
153
154 writel(TRNG_INTACK_REG_READY, &ks_sa_rng->reg_rng->intack);
155
156 return sizeof(u32) * 2;
157 }
158
ks_sa_rng_data_present(struct hwrng * rng,int wait)159 static int ks_sa_rng_data_present(struct hwrng *rng, int wait)
160 {
161 struct device *dev = (struct device *)rng->priv;
162 struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
163
164 u32 ready;
165 int j;
166
167 for (j = 0; j < SA_MAX_RNG_DATA_RETRIES; j++) {
168 ready = readl(&ks_sa_rng->reg_rng->status);
169 ready &= TRNG_STATUS_REG_READY;
170
171 if (ready || !wait)
172 break;
173
174 udelay(SA_RNG_DATA_RETRY_DELAY);
175 }
176
177 return ready;
178 }
179
ks_sa_rng_probe(struct platform_device * pdev)180 static int ks_sa_rng_probe(struct platform_device *pdev)
181 {
182 struct ks_sa_rng *ks_sa_rng;
183 struct device *dev = &pdev->dev;
184 int ret;
185 struct resource *mem;
186
187 ks_sa_rng = devm_kzalloc(dev, sizeof(*ks_sa_rng), GFP_KERNEL);
188 if (!ks_sa_rng)
189 return -ENOMEM;
190
191 ks_sa_rng->dev = dev;
192 ks_sa_rng->rng = (struct hwrng) {
193 .name = "ks_sa_hwrng",
194 .init = ks_sa_rng_init,
195 .data_read = ks_sa_rng_data_read,
196 .data_present = ks_sa_rng_data_present,
197 .cleanup = ks_sa_rng_cleanup,
198 };
199 ks_sa_rng->rng.priv = (unsigned long)dev;
200
201 mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
202 ks_sa_rng->reg_rng = devm_ioremap_resource(dev, mem);
203 if (IS_ERR(ks_sa_rng->reg_rng))
204 return PTR_ERR(ks_sa_rng->reg_rng);
205
206 ks_sa_rng->regmap_cfg =
207 syscon_regmap_lookup_by_phandle(dev->of_node,
208 "ti,syscon-sa-cfg");
209
210 if (IS_ERR(ks_sa_rng->regmap_cfg)) {
211 dev_err(dev, "syscon_node_to_regmap failed\n");
212 return -EINVAL;
213 }
214
215 pm_runtime_enable(dev);
216 ret = pm_runtime_get_sync(dev);
217 if (ret < 0) {
218 dev_err(dev, "Failed to enable SA power-domain\n");
219 pm_runtime_disable(dev);
220 return ret;
221 }
222
223 platform_set_drvdata(pdev, ks_sa_rng);
224
225 return devm_hwrng_register(&pdev->dev, &ks_sa_rng->rng);
226 }
227
ks_sa_rng_remove(struct platform_device * pdev)228 static int ks_sa_rng_remove(struct platform_device *pdev)
229 {
230 pm_runtime_put_sync(&pdev->dev);
231 pm_runtime_disable(&pdev->dev);
232
233 return 0;
234 }
235
236 static const struct of_device_id ks_sa_rng_dt_match[] = {
237 {
238 .compatible = "ti,keystone-rng",
239 },
240 { },
241 };
242 MODULE_DEVICE_TABLE(of, ks_sa_rng_dt_match);
243
244 static struct platform_driver ks_sa_rng_driver = {
245 .driver = {
246 .name = "ks-sa-rng",
247 .of_match_table = ks_sa_rng_dt_match,
248 },
249 .probe = ks_sa_rng_probe,
250 .remove = ks_sa_rng_remove,
251 };
252
253 module_platform_driver(ks_sa_rng_driver);
254
255 MODULE_DESCRIPTION("Keystone NETCP SA H/W Random Number Generator driver");
256 MODULE_AUTHOR("Vitaly Andrianov <vitalya@ti.com>");
257 MODULE_LICENSE("GPL");
258
