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
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 hwrng rng;
85 struct clk *clk;
86 struct regmap *regmap_cfg;
87 struct trng_regs __iomem *reg_rng;
88 u64 ready_ts;
89 unsigned int refill_delay_ns;
90};
91
92static unsigned int cycles_to_ns(unsigned long clk_rate, unsigned int cycles)
93{
94 return DIV_ROUND_UP_ULL((TRNG_DEF_CLK_DIV_CYCLES + 1) * 1000000000ull *
95 cycles, clk_rate);
96}
97
98static unsigned int startup_delay_ns(unsigned long clk_rate)
99{
100 if (!TRNG_DEF_STARTUP_CYCLES)
101 return cycles_to_ns(clk_rate, BIT(24));
102 return cycles_to_ns(clk_rate, cycles: 256 * TRNG_DEF_STARTUP_CYCLES);
103}
104
105static unsigned int refill_delay_ns(unsigned long clk_rate)
106{
107 if (!TRNG_DEF_MAX_REFILL_CYCLES)
108 return cycles_to_ns(clk_rate, BIT(24));
109 return cycles_to_ns(clk_rate, cycles: 256 * TRNG_DEF_MAX_REFILL_CYCLES);
110}
111
112static int ks_sa_rng_init(struct hwrng *rng)
113{
114 u32 value;
115 struct ks_sa_rng *ks_sa_rng = container_of(rng, struct ks_sa_rng, rng);
116 unsigned long clk_rate = clk_get_rate(clk: ks_sa_rng->clk);
117
118 /* Enable RNG module */
119 regmap_write_bits(map: ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,
120 SA_CMD_STATUS_REG_TRNG_ENABLE,
121 SA_CMD_STATUS_REG_TRNG_ENABLE);
122
123 /* Configure RNG module */
124 writel(val: 0, addr: &ks_sa_rng->reg_rng->control);
125 value = TRNG_DEF_STARTUP_CYCLES << TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT;
126 writel(val: value, addr: &ks_sa_rng->reg_rng->control);
127
128 value = (TRNG_DEF_MIN_REFILL_CYCLES <<
129 TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT) |
130 (TRNG_DEF_MAX_REFILL_CYCLES <<
131 TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT) |
132 (TRNG_DEF_CLK_DIV_CYCLES <<
133 TRNG_CFG_REG_SAMPLE_DIV_SHIFT);
134
135 writel(val: value, addr: &ks_sa_rng->reg_rng->config);
136
137 /* Disable all interrupts from TRNG */
138 writel(val: 0, addr: &ks_sa_rng->reg_rng->intmask);
139
140 /* Enable RNG */
141 value = readl(addr: &ks_sa_rng->reg_rng->control);
142 value |= TRNG_CNTL_REG_TRNG_ENABLE;
143 writel(val: value, addr: &ks_sa_rng->reg_rng->control);
144
145 ks_sa_rng->refill_delay_ns = refill_delay_ns(clk_rate);
146 ks_sa_rng->ready_ts = ktime_get_ns() +
147 startup_delay_ns(clk_rate);
148
149 return 0;
150}
151
152static void ks_sa_rng_cleanup(struct hwrng *rng)
153{
154 struct ks_sa_rng *ks_sa_rng = container_of(rng, struct ks_sa_rng, rng);
155
156 /* Disable RNG */
157 writel(val: 0, addr: &ks_sa_rng->reg_rng->control);
158 regmap_write_bits(map: ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,
159 SA_CMD_STATUS_REG_TRNG_ENABLE, val: 0);
160}
161
162static int ks_sa_rng_data_read(struct hwrng *rng, u32 *data)
163{
164 struct ks_sa_rng *ks_sa_rng = container_of(rng, struct ks_sa_rng, rng);
165
166 /* Read random data */
167 data[0] = readl(addr: &ks_sa_rng->reg_rng->output_l);
168 data[1] = readl(addr: &ks_sa_rng->reg_rng->output_h);
169
170 writel(TRNG_INTACK_REG_READY, addr: &ks_sa_rng->reg_rng->intack);
171 ks_sa_rng->ready_ts = ktime_get_ns() + ks_sa_rng->refill_delay_ns;
172
173 return sizeof(u32) * 2;
174}
175
176static int ks_sa_rng_data_present(struct hwrng *rng, int wait)
177{
178 struct ks_sa_rng *ks_sa_rng = container_of(rng, struct ks_sa_rng, rng);
179 u64 now = ktime_get_ns();
180
181 u32 ready;
182 int j;
183
184 if (wait && now < ks_sa_rng->ready_ts) {
185 /* Max delay expected here is 81920000 ns */
186 unsigned long min_delay =
187 DIV_ROUND_UP((u32)(ks_sa_rng->ready_ts - now), 1000);
188
189 usleep_range(min: min_delay, max: min_delay + SA_RNG_DATA_RETRY_DELAY);
190 }
191
192 for (j = 0; j < SA_MAX_RNG_DATA_RETRIES; j++) {
193 ready = readl(addr: &ks_sa_rng->reg_rng->status);
194 ready &= TRNG_STATUS_REG_READY;
195
196 if (ready || !wait)
197 break;
198
199 udelay(SA_RNG_DATA_RETRY_DELAY);
200 }
201
202 return ready;
203}
204
205static int ks_sa_rng_probe(struct platform_device *pdev)
206{
207 struct ks_sa_rng *ks_sa_rng;
208 struct device *dev = &pdev->dev;
209 int ret;
210
211 ks_sa_rng = devm_kzalloc(dev, size: sizeof(*ks_sa_rng), GFP_KERNEL);
212 if (!ks_sa_rng)
213 return -ENOMEM;
214
215 ks_sa_rng->rng = (struct hwrng) {
216 .name = "ks_sa_hwrng",
217 .init = ks_sa_rng_init,
218 .data_read = ks_sa_rng_data_read,
219 .data_present = ks_sa_rng_data_present,
220 .cleanup = ks_sa_rng_cleanup,
221 };
222
223 ks_sa_rng->reg_rng = devm_platform_ioremap_resource(pdev, index: 0);
224 if (IS_ERR(ptr: ks_sa_rng->reg_rng))
225 return PTR_ERR(ptr: ks_sa_rng->reg_rng);
226
227 ks_sa_rng->regmap_cfg =
228 syscon_regmap_lookup_by_phandle(np: dev->of_node,
229 property: "ti,syscon-sa-cfg");
230
231 if (IS_ERR(ptr: ks_sa_rng->regmap_cfg))
232 return dev_err_probe(dev, err: -EINVAL, fmt: "syscon_node_to_regmap failed\n");
233
234 pm_runtime_enable(dev);
235 ret = pm_runtime_resume_and_get(dev);
236 if (ret < 0) {
237 pm_runtime_disable(dev);
238 return dev_err_probe(dev, err: ret, fmt: "Failed to enable SA power-domain\n");
239 }
240
241 return devm_hwrng_register(dev: &pdev->dev, rng: &ks_sa_rng->rng);
242}
243
244static int ks_sa_rng_remove(struct platform_device *pdev)
245{
246 pm_runtime_put_sync(dev: &pdev->dev);
247 pm_runtime_disable(dev: &pdev->dev);
248
249 return 0;
250}
251
252static const struct of_device_id ks_sa_rng_dt_match[] = {
253 {
254 .compatible = "ti,keystone-rng",
255 },
256 { },
257};
258MODULE_DEVICE_TABLE(of, ks_sa_rng_dt_match);
259
260static struct platform_driver ks_sa_rng_driver = {
261 .driver = {
262 .name = "ks-sa-rng",
263 .of_match_table = ks_sa_rng_dt_match,
264 },
265 .probe = ks_sa_rng_probe,
266 .remove = ks_sa_rng_remove,
267};
268
269module_platform_driver(ks_sa_rng_driver);
270
271MODULE_DESCRIPTION("Keystone NETCP SA H/W Random Number Generator driver");
272MODULE_AUTHOR("Vitaly Andrianov <vitalya@ti.com>");
273MODULE_LICENSE("GPL");
274

source code of linux/drivers/char/hw_random/ks-sa-rng.c