hwrng: atmel - add new platform support for sam9x60

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 <codrin.ciubotariu@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

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_data {
+	bool has_half_rate;
+};
+
 struct atmel_trng {
 	struct clk *clk;
 	void __iomem *base;
@@ -62,6 +70,7 @@ static void atmel_trng_disable(struct atmel_trng *trng)
 static int atmel_trng_probe(struct platform_device *pdev)
 {
 	struct atmel_trng *trng;
+	const struct atmel_trng_data *data;
 	int ret;
 
 	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
@@ -75,6 +84,17 @@ 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);
+	data = of_device_get_match_data(&pdev->dev);
+	if (!data)
+		return -ENODEV;
+
+	if (data->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)
@@ -139,9 +159,24 @@ static const struct dev_pm_ops atmel_trng_pm_ops = {
 };
 #endif /* CONFIG_PM */
 
+static const struct atmel_trng_data at91sam9g45_config = {
+	.has_half_rate = false,
+};
+
+static const struct atmel_trng_data 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);