1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Random Number Generator driver for the Keystone SOC
4 *
5 * Copyright (C) 2016 Texas Instruments Incorporated - https://www.ti.com
6 *
7 * Authors: Sandeep Nair
8 * Vitaly Andrianov
9 */
10
11 #include <linux/hw_random.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/io.h>
15 #include <linux/platform_device.h>
16 #include <linux/clk.h>
17 #include <linux/pm_runtime.h>
18 #include <linux/err.h>
19 #include <linux/regmap.h>
20 #include <linux/mfd/syscon.h>
21 #include <linux/of.h>
22 #include <linux/of_address.h>
23 #include <linux/delay.h>
24 #include <linux/timekeeping.h>
25
26 #define SA_CMD_STATUS_OFS 0x8
27
28 /* TRNG enable control in SA System module*/
29 #define SA_CMD_STATUS_REG_TRNG_ENABLE BIT(3)
30
31 /* TRNG start control in TRNG module */
32 #define TRNG_CNTL_REG_TRNG_ENABLE BIT(10)
33
34 /* Data ready indicator in STATUS register */
35 #define TRNG_STATUS_REG_READY BIT(0)
36
37 /* Data ready clear control in INTACK register */
38 #define TRNG_INTACK_REG_READY BIT(0)
39
40 /*
41 * Number of samples taken to gather entropy during startup.
42 * If value is 0, the number of samples is 2^24 else
43 * equals value times 2^8.
44 */
45 #define TRNG_DEF_STARTUP_CYCLES 0
46 #define TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT 16
47
48 /*
49 * Minimum number of samples taken to regenerate entropy
50 * If value is 0, the number of samples is 2^24 else
51 * equals value times 2^6.
52 */
53 #define TRNG_DEF_MIN_REFILL_CYCLES 1
54 #define TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT 0
55
56 /*
57 * Maximum number of samples taken to regenerate entropy
58 * If value is 0, the number of samples is 2^24 else
59 * equals value times 2^8.
60 */
61 #define TRNG_DEF_MAX_REFILL_CYCLES 0
62 #define TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT 16
63
64 /* Number of CLK input cycles between samples */
65 #define TRNG_DEF_CLK_DIV_CYCLES 0
66 #define TRNG_CFG_REG_SAMPLE_DIV_SHIFT 8
67
68 /* Maximum retries to get rng data */
69 #define SA_MAX_RNG_DATA_RETRIES 5
70 /* Delay between retries (in usecs) */
71 #define SA_RNG_DATA_RETRY_DELAY 5
72
73 struct trng_regs {
74 u32 output_l;
75 u32 output_h;
76 u32 status;
77 u32 intmask;
78 u32 intack;
79 u32 control;
80 u32 config;
81 };
82
83 struct ks_sa_rng {
84 struct device *dev;
85 struct hwrng rng;
86 struct clk *clk;
87 struct regmap *regmap_cfg;
88 struct trng_regs __iomem *reg_rng;
89 u64 ready_ts;
90 unsigned int refill_delay_ns;
91 };
92
cycles_to_ns(unsigned long clk_rate,unsigned int cycles)93 static unsigned int cycles_to_ns(unsigned long clk_rate, unsigned int cycles)
94 {
95 return DIV_ROUND_UP_ULL((TRNG_DEF_CLK_DIV_CYCLES + 1) * 1000000000ull *
96 cycles, clk_rate);
97 }
98
startup_delay_ns(unsigned long clk_rate)99 static unsigned int startup_delay_ns(unsigned long clk_rate)
100 {
101 if (!TRNG_DEF_STARTUP_CYCLES)
102 return cycles_to_ns(clk_rate, BIT(24));
103 return cycles_to_ns(clk_rate, 256 * TRNG_DEF_STARTUP_CYCLES);
104 }
105
refill_delay_ns(unsigned long clk_rate)106 static unsigned int refill_delay_ns(unsigned long clk_rate)
107 {
108 if (!TRNG_DEF_MAX_REFILL_CYCLES)
109 return cycles_to_ns(clk_rate, BIT(24));
110 return cycles_to_ns(clk_rate, 256 * TRNG_DEF_MAX_REFILL_CYCLES);
111 }
112
ks_sa_rng_init(struct hwrng * rng)113 static int ks_sa_rng_init(struct hwrng *rng)
114 {
115 u32 value;
116 struct device *dev = (struct device *)rng->priv;
117 struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
118 unsigned long clk_rate = clk_get_rate(ks_sa_rng->clk);
119
120 /* Enable RNG module */
121 regmap_write_bits(ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,
122 SA_CMD_STATUS_REG_TRNG_ENABLE,
123 SA_CMD_STATUS_REG_TRNG_ENABLE);
124
125 /* Configure RNG module */
126 writel(0, &ks_sa_rng->reg_rng->control);
127 value = TRNG_DEF_STARTUP_CYCLES << TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT;
128 writel(value, &ks_sa_rng->reg_rng->control);
129
130 value = (TRNG_DEF_MIN_REFILL_CYCLES <<
131 TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT) |
132 (TRNG_DEF_MAX_REFILL_CYCLES <<
133 TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT) |
134 (TRNG_DEF_CLK_DIV_CYCLES <<
135 TRNG_CFG_REG_SAMPLE_DIV_SHIFT);
136
137 writel(value, &ks_sa_rng->reg_rng->config);
138
139 /* Disable all interrupts from TRNG */
140 writel(0, &ks_sa_rng->reg_rng->intmask);
141
142 /* Enable RNG */
143 value = readl(&ks_sa_rng->reg_rng->control);
144 value |= TRNG_CNTL_REG_TRNG_ENABLE;
145 writel(value, &ks_sa_rng->reg_rng->control);
146
147 ks_sa_rng->refill_delay_ns = refill_delay_ns(clk_rate);
148 ks_sa_rng->ready_ts = ktime_get_ns() +
149 startup_delay_ns(clk_rate);
150
151 return 0;
152 }
153
ks_sa_rng_cleanup(struct hwrng * rng)154 static void ks_sa_rng_cleanup(struct hwrng *rng)
155 {
156 struct device *dev = (struct device *)rng->priv;
157 struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
158
159 /* Disable RNG */
160 writel(0, &ks_sa_rng->reg_rng->control);
161 regmap_write_bits(ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,
162 SA_CMD_STATUS_REG_TRNG_ENABLE, 0);
163 }
164
ks_sa_rng_data_read(struct hwrng * rng,u32 * data)165 static int ks_sa_rng_data_read(struct hwrng *rng, u32 *data)
166 {
167 struct device *dev = (struct device *)rng->priv;
168 struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
169
170 /* Read random data */
171 data[0] = readl(&ks_sa_rng->reg_rng->output_l);
172 data[1] = readl(&ks_sa_rng->reg_rng->output_h);
173
174 writel(TRNG_INTACK_REG_READY, &ks_sa_rng->reg_rng->intack);
175 ks_sa_rng->ready_ts = ktime_get_ns() + ks_sa_rng->refill_delay_ns;
176
177 return sizeof(u32) * 2;
178 }
179
ks_sa_rng_data_present(struct hwrng * rng,int wait)180 static int ks_sa_rng_data_present(struct hwrng *rng, int wait)
181 {
182 struct device *dev = (struct device *)rng->priv;
183 struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
184 u64 now = ktime_get_ns();
185
186 u32 ready;
187 int j;
188
189 if (wait && now < ks_sa_rng->ready_ts) {
190 /* Max delay expected here is 81920000 ns */
191 unsigned long min_delay =
192 DIV_ROUND_UP((u32)(ks_sa_rng->ready_ts - now), 1000);
193
194 usleep_range(min_delay, min_delay + SA_RNG_DATA_RETRY_DELAY);
195 }
196
197 for (j = 0; j < SA_MAX_RNG_DATA_RETRIES; j++) {
198 ready = readl(&ks_sa_rng->reg_rng->status);
199 ready &= TRNG_STATUS_REG_READY;
200
201 if (ready || !wait)
202 break;
203
204 udelay(SA_RNG_DATA_RETRY_DELAY);
205 }
206
207 return ready;
208 }
209
ks_sa_rng_probe(struct platform_device * pdev)210 static int ks_sa_rng_probe(struct platform_device *pdev)
211 {
212 struct ks_sa_rng *ks_sa_rng;
213 struct device *dev = &pdev->dev;
214 int ret;
215
216 ks_sa_rng = devm_kzalloc(dev, sizeof(*ks_sa_rng), GFP_KERNEL);
217 if (!ks_sa_rng)
218 return -ENOMEM;
219
220 ks_sa_rng->dev = dev;
221 ks_sa_rng->rng = (struct hwrng) {
222 .name = "ks_sa_hwrng",
223 .init = ks_sa_rng_init,
224 .data_read = ks_sa_rng_data_read,
225 .data_present = ks_sa_rng_data_present,
226 .cleanup = ks_sa_rng_cleanup,
227 };
228 ks_sa_rng->rng.priv = (unsigned long)dev;
229
230 ks_sa_rng->reg_rng = devm_platform_ioremap_resource(pdev, 0);
231 if (IS_ERR(ks_sa_rng->reg_rng))
232 return PTR_ERR(ks_sa_rng->reg_rng);
233
234 ks_sa_rng->regmap_cfg =
235 syscon_regmap_lookup_by_phandle(dev->of_node,
236 "ti,syscon-sa-cfg");
237
238 if (IS_ERR(ks_sa_rng->regmap_cfg)) {
239 dev_err(dev, "syscon_node_to_regmap failed\n");
240 return -EINVAL;
241 }
242
243 pm_runtime_enable(dev);
244 ret = pm_runtime_resume_and_get(dev);
245 if (ret < 0) {
246 dev_err(dev, "Failed to enable SA power-domain\n");
247 pm_runtime_disable(dev);
248 return ret;
249 }
250
251 platform_set_drvdata(pdev, ks_sa_rng);
252
253 return devm_hwrng_register(&pdev->dev, &ks_sa_rng->rng);
254 }
255
ks_sa_rng_remove(struct platform_device * pdev)256 static int ks_sa_rng_remove(struct platform_device *pdev)
257 {
258 pm_runtime_put_sync(&pdev->dev);
259 pm_runtime_disable(&pdev->dev);
260
261 return 0;
262 }
263
264 static const struct of_device_id ks_sa_rng_dt_match[] = {
265 {
266 .compatible = "ti,keystone-rng",
267 },
268 { },
269 };
270 MODULE_DEVICE_TABLE(of, ks_sa_rng_dt_match);
271
272 static struct platform_driver ks_sa_rng_driver = {
273 .driver = {
274 .name = "ks-sa-rng",
275 .of_match_table = ks_sa_rng_dt_match,
276 },
277 .probe = ks_sa_rng_probe,
278 .remove = ks_sa_rng_remove,
279 };
280
281 module_platform_driver(ks_sa_rng_driver);
282
283 MODULE_DESCRIPTION("Keystone NETCP SA H/W Random Number Generator driver");
284 MODULE_AUTHOR("Vitaly Andrianov <vitalya@ti.com>");
285 MODULE_LICENSE("GPL");
286