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199 lines
4.2 KiB
199 lines
4.2 KiB
/* |
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* Copyright (c) 2011 Peter Korsgaard <[email protected]> |
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* |
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* This file is licensed under the terms of the GNU General Public |
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* License version 2. This program is licensed "as is" without any |
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* warranty of any kind, whether express or implied. |
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*/ |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/mod_devicetable.h> |
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#include <linux/slab.h> |
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#include <linux/err.h> |
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#include <linux/clk.h> |
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#include <linux/io.h> |
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#include <linux/hw_random.h> |
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#include <linux/of_device.h> |
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#include <linux/platform_device.h> |
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#define TRNG_CR 0x00 |
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#define TRNG_MR 0x04 |
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#define TRNG_ISR 0x1c |
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#define TRNG_ODATA 0x50 |
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#define TRNG_KEY 0x524e4700 /* RNG */ |
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#define TRNG_HALFR BIT(0) /* generate RN every 168 cycles */ |
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struct atmel_trng_data { |
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bool has_half_rate; |
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}; |
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struct atmel_trng { |
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struct clk *clk; |
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void __iomem *base; |
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struct hwrng rng; |
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}; |
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static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max, |
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bool wait) |
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{ |
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struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng); |
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u32 *data = buf; |
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/* data ready? */ |
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if (readl(trng->base + TRNG_ISR) & 1) { |
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*data = readl(trng->base + TRNG_ODATA); |
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/* |
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ensure data ready is only set again AFTER the next data |
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word is ready in case it got set between checking ISR |
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and reading ODATA, so we don't risk re-reading the |
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same word |
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*/ |
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readl(trng->base + TRNG_ISR); |
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return 4; |
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} else |
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return 0; |
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} |
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static void atmel_trng_enable(struct atmel_trng *trng) |
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{ |
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writel(TRNG_KEY | 1, trng->base + TRNG_CR); |
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} |
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static void atmel_trng_disable(struct atmel_trng *trng) |
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{ |
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writel(TRNG_KEY, trng->base + TRNG_CR); |
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} |
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static int atmel_trng_probe(struct platform_device *pdev) |
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{ |
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struct atmel_trng *trng; |
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const struct atmel_trng_data *data; |
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int ret; |
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trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL); |
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if (!trng) |
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return -ENOMEM; |
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trng->base = devm_platform_ioremap_resource(pdev, 0); |
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if (IS_ERR(trng->base)) |
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return PTR_ERR(trng->base); |
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trng->clk = devm_clk_get(&pdev->dev, NULL); |
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if (IS_ERR(trng->clk)) |
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return PTR_ERR(trng->clk); |
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data = of_device_get_match_data(&pdev->dev); |
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if (!data) |
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return -ENODEV; |
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if (data->has_half_rate) { |
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unsigned long rate = clk_get_rate(trng->clk); |
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/* if peripheral clk is above 100MHz, set HALFR */ |
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if (rate > 100000000) |
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writel(TRNG_HALFR, trng->base + TRNG_MR); |
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} |
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ret = clk_prepare_enable(trng->clk); |
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if (ret) |
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return ret; |
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atmel_trng_enable(trng); |
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trng->rng.name = pdev->name; |
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trng->rng.read = atmel_trng_read; |
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ret = devm_hwrng_register(&pdev->dev, &trng->rng); |
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if (ret) |
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goto err_register; |
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platform_set_drvdata(pdev, trng); |
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return 0; |
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err_register: |
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clk_disable_unprepare(trng->clk); |
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return ret; |
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} |
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static int atmel_trng_remove(struct platform_device *pdev) |
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{ |
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struct atmel_trng *trng = platform_get_drvdata(pdev); |
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atmel_trng_disable(trng); |
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clk_disable_unprepare(trng->clk); |
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return 0; |
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} |
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#ifdef CONFIG_PM |
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static int atmel_trng_suspend(struct device *dev) |
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{ |
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struct atmel_trng *trng = dev_get_drvdata(dev); |
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atmel_trng_disable(trng); |
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clk_disable_unprepare(trng->clk); |
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return 0; |
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} |
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static int atmel_trng_resume(struct device *dev) |
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{ |
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struct atmel_trng *trng = dev_get_drvdata(dev); |
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int ret; |
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ret = clk_prepare_enable(trng->clk); |
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if (ret) |
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return ret; |
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atmel_trng_enable(trng); |
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return 0; |
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} |
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static const struct dev_pm_ops atmel_trng_pm_ops = { |
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.suspend = atmel_trng_suspend, |
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.resume = atmel_trng_resume, |
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}; |
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#endif /* CONFIG_PM */ |
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static const struct atmel_trng_data at91sam9g45_config = { |
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.has_half_rate = false, |
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}; |
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static const struct atmel_trng_data sam9x60_config = { |
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.has_half_rate = true, |
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}; |
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static const struct of_device_id atmel_trng_dt_ids[] = { |
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{ |
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.compatible = "atmel,at91sam9g45-trng", |
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.data = &at91sam9g45_config, |
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}, { |
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.compatible = "microchip,sam9x60-trng", |
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.data = &sam9x60_config, |
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}, { |
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/* sentinel */ |
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} |
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}; |
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MODULE_DEVICE_TABLE(of, atmel_trng_dt_ids); |
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static struct platform_driver atmel_trng_driver = { |
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.probe = atmel_trng_probe, |
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.remove = atmel_trng_remove, |
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.driver = { |
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.name = "atmel-trng", |
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#ifdef CONFIG_PM |
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.pm = &atmel_trng_pm_ops, |
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#endif /* CONFIG_PM */ |
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.of_match_table = atmel_trng_dt_ids, |
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}, |
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}; |
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module_platform_driver(atmel_trng_driver); |
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MODULE_LICENSE("GPL"); |
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MODULE_AUTHOR("Peter Korsgaard <[email protected]>"); |
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MODULE_DESCRIPTION("Atmel true random number generator driver");
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