1 // SPDX-License-Identifier: GPL-2.0-only
3  * drivers/char/hw_random/timeriomem-rng.c
7  * Derived from drivers/char/hw_random/omap-rng.c
12  *   This driver is useful for platforms that have an IO range that provides
31 #include <linux/timeriomem-rng.h>
50 	int period_us = ktime_to_us(priv->period);  in timeriomem_rng_read()
58 	if (!wait && !priv->present)  in timeriomem_rng_read()
61 	wait_for_completion(&priv->completion);  in timeriomem_rng_read()
67 		 * a wide range of values (1us to 1s have been observed), allow  in timeriomem_rng_read()
74 		*(u32 *)data = readl(priv->io_base);  in timeriomem_rng_read()
77 		max -= sizeof(u32);  in timeriomem_rng_read()
84 	priv->present = 0;  in timeriomem_rng_read()
85 	reinit_completion(&priv->completion);  in timeriomem_rng_read()
86 	hrtimer_forward_now(&priv->timer, priv->period);  in timeriomem_rng_read()
87 	hrtimer_restart(&priv->timer);  in timeriomem_rng_read()
97 	priv->present = 1;  in timeriomem_rng_trigger()
98 	complete(&priv->completion);  in timeriomem_rng_trigger()
105 	struct timeriomem_rng_data *pdata = pdev->dev.platform_data;  in timeriomem_rng_probe()
111 	if (!pdev->dev.of_node && !pdata) {  in timeriomem_rng_probe()
112 		dev_err(&pdev->dev, "timeriomem_rng_data is missing\n");  in timeriomem_rng_probe()
113 		return -EINVAL;  in timeriomem_rng_probe()
118 		return -ENXIO;  in timeriomem_rng_probe()
120 	if (res->start % 4 != 0 || resource_size(res) < 4) {  in timeriomem_rng_probe()
121 		dev_err(&pdev->dev,  in timeriomem_rng_probe()
122 			"address must be at least four bytes wide and 32-bit aligned\n");  in timeriomem_rng_probe()
123 		return -EINVAL;  in timeriomem_rng_probe()
127 	priv = devm_kzalloc(&pdev->dev,  in timeriomem_rng_probe()
130 		return -ENOMEM;  in timeriomem_rng_probe()
134 	if (pdev->dev.of_node) {  in timeriomem_rng_probe()
137 		if (!of_property_read_u32(pdev->dev.of_node,  in timeriomem_rng_probe()
141 			dev_err(&pdev->dev, "missing period\n");  in timeriomem_rng_probe()
142 			return -EINVAL;  in timeriomem_rng_probe()
145 		if (!of_property_read_u32(pdev->dev.of_node,  in timeriomem_rng_probe()
147 			priv->rng_ops.quality = i;  in timeriomem_rng_probe()
149 			priv->rng_ops.quality = 0;  in timeriomem_rng_probe()
151 		period = pdata->period;  in timeriomem_rng_probe()
152 		priv->rng_ops.quality = pdata->quality;  in timeriomem_rng_probe()
155 	priv->period = ns_to_ktime(period * NSEC_PER_USEC);  in timeriomem_rng_probe()
156 	init_completion(&priv->completion);  in timeriomem_rng_probe()
157 	hrtimer_init(&priv->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);  in timeriomem_rng_probe()
158 	priv->timer.function = timeriomem_rng_trigger;  in timeriomem_rng_probe()
160 	priv->rng_ops.name = dev_name(&pdev->dev);  in timeriomem_rng_probe()
161 	priv->rng_ops.read = timeriomem_rng_read;  in timeriomem_rng_probe()
163 	priv->io_base = devm_ioremap_resource(&pdev->dev, res);  in timeriomem_rng_probe()
164 	if (IS_ERR(priv->io_base)) {  in timeriomem_rng_probe()
165 		return PTR_ERR(priv->io_base);  in timeriomem_rng_probe()
169 	priv->present = 1;  in timeriomem_rng_probe()
170 	complete(&priv->completion);  in timeriomem_rng_probe()
172 	err = devm_hwrng_register(&pdev->dev, &priv->rng_ops);  in timeriomem_rng_probe()
174 		dev_err(&pdev->dev, "problem registering\n");  in timeriomem_rng_probe()
178 	dev_info(&pdev->dev, "32bits from 0x%p @ %dus\n",  in timeriomem_rng_probe()
179 			priv->io_base, period);  in timeriomem_rng_probe()
188 	hrtimer_cancel(&priv->timer);  in timeriomem_rng_remove()