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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
29#define SA_CMD_STATUS_REG_TRNG_ENABLE BIT(3)
30
31
32#define TRNG_CNTL_REG_TRNG_ENABLE BIT(10)
33
34
35#define TRNG_STATUS_REG_READY BIT(0)
36
37
38#define TRNG_INTACK_REG_READY BIT(0)
39
40
41
42
43
44
45#define TRNG_DEF_STARTUP_CYCLES 0
46#define TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT 16
47
48
49
50
51
52
53#define TRNG_DEF_MIN_REFILL_CYCLES 1
54#define TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT 0
55
56
57
58
59
60
61#define TRNG_DEF_MAX_REFILL_CYCLES 0
62#define TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT 16
63
64
65#define TRNG_DEF_CLK_DIV_CYCLES 0
66#define TRNG_CFG_REG_SAMPLE_DIV_SHIFT 8
67
68
69#define SA_MAX_RNG_DATA_RETRIES 5
70
71#define SA_RNG_DATA_RETRY_DELAY 5
72
73struct 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
83struct 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
93static 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
99static 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
106static 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
113static 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
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
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
140 writel(0, &ks_sa_rng->reg_rng->intmask);
141
142
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
154static 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
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
165static 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
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
180static 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
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
210static 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_get_sync(dev);
245 if (ret < 0) {
246 dev_err(dev, "Failed to enable SA power-domain\n");
247 pm_runtime_put_noidle(dev);
248 pm_runtime_disable(dev);
249 return ret;
250 }
251
252 platform_set_drvdata(pdev, ks_sa_rng);
253
254 return devm_hwrng_register(&pdev->dev, &ks_sa_rng->rng);
255}
256
257static int ks_sa_rng_remove(struct platform_device *pdev)
258{
259 pm_runtime_put_sync(&pdev->dev);
260 pm_runtime_disable(&pdev->dev);
261
262 return 0;
263}
264
265static const struct of_device_id ks_sa_rng_dt_match[] = {
266 {
267 .compatible = "ti,keystone-rng",
268 },
269 { },
270};
271MODULE_DEVICE_TABLE(of, ks_sa_rng_dt_match);
272
273static struct platform_driver ks_sa_rng_driver = {
274 .driver = {
275 .name = "ks-sa-rng",
276 .of_match_table = ks_sa_rng_dt_match,
277 },
278 .probe = ks_sa_rng_probe,
279 .remove = ks_sa_rng_remove,
280};
281
282module_platform_driver(ks_sa_rng_driver);
283
284MODULE_DESCRIPTION("Keystone NETCP SA H/W Random Number Generator driver");
285MODULE_AUTHOR("Vitaly Andrianov <vitalya@ti.com>");
286MODULE_LICENSE("GPL");
287
