Subject: [PATCH 2/2] hwrng: atmel: add new platform support for sam9x60

From: Codrin Ciubotariu <[email-masked]>
Date: Thu, 24 Oct 2019 20:04:52 +0300

Add platform support for the new IP found on sam9x60 SoC. For this
version, if the peripheral clk is above 100MHz, the HALFR bit must be
set. This bit is available only if the IP can generate a random number
every 168 cycles (instead of 84).

Signed-off-by: Codrin Ciubotariu <[email-masked]>
---
 drivers/char/hw_random/atmel-rng.c | 39 ++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
index e55705745d5e..0aa9425e6c3e 100644
--- a/drivers/char/hw_random/atmel-rng.c
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -14,14 +14,22 @@
 #include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/hw_random.h>
+#include <linux/of_device.h>
 #include <linux/platform_device.h>
 
 #define TRNG_CR		0x00
+#define TRNG_MR		0x04
 #define TRNG_ISR	0x1c
 #define TRNG_ODATA	0x50
 
 #define TRNG_KEY	0x524e4700 /* RNG */
 
+#define TRNG_HALFR	BIT(0) /* generate RN every 168 cycles */
+
+struct atmel_trng_pdata {
+	bool has_half_rate;
+};
+
 struct atmel_trng {
 	struct clk *clk;
 	void __iomem *base;
@@ -63,6 +71,7 @@ static int atmel_trng_probe(struct platform_device *pdev)
 {
 	struct atmel_trng *trng;
 	struct resource *res;
+	const struct atmel_trng_pdata *pdata;
 	int ret;
 
 	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
@@ -77,6 +86,17 @@ static int atmel_trng_probe(struct platform_device *pdev)
 	trng->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(trng->clk))
 		return PTR_ERR(trng->clk);
+	pdata = of_device_get_match_data(&pdev->dev);
+	if (!pdata)
+		return -ENODEV;
+
+	if (pdata->has_half_rate) {
+		unsigned long rate = clk_get_rate(trng->clk);
+
+		/* if peripheral clk is above 100MHz, set HALFR */
+		if (rate > 100000000)
+			writel(TRNG_HALFR, trng->base + TRNG_MR);
+	}
 
 	ret = clk_prepare_enable(trng->clk);
 	if (ret)
@@ -141,9 +161,24 @@ static const struct dev_pm_ops atmel_trng_pm_ops = {
 };
 #endif /* CONFIG_PM */
 
+static struct atmel_trng_pdata at91sam9g45_config = {
+	.has_half_rate = false,
+};
+
+static struct atmel_trng_pdata sam9x60_config = {
+	.has_half_rate = true,
+};
+
 static const struct of_device_id atmel_trng_dt_ids[] = {
-	{ .compatible = "atmel,at91sam9g45-trng" },
-	{ /* sentinel */ }
+	{
+		.compatible = "atmel,at91sam9g45-trng",
+		.data = &at91sam9g45_config,
+	}, {
+		.compatible = "microchip,sam9x60-trng",
+		.data = &sam9x60_config,
+	}, {
+		/* sentinel */
+	}
 };
 MODULE_DEVICE_TABLE(of, atmel_trng_dt_ids);
 
-- 
2.20.1

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