[PATCH v3 6/6] crypto: qcom: Add ACPI support

[Vinod Koul <vkoul@kernel.org>]

From: Timur Tabi <timur@codeaurora.org>

Add support for probing on ACPI systems, with ACPI HID QCOM8160.

On ACPI systems, clocks are always enabled, the PRNG should
already be enabled, and the register region is read-only.
The driver only verifies that the hardware is already
enabled never tries to disable or configure it.

Signed-off-by: Timur Tabi <timur@codeaurora.org>
[port to crypto API]
Signed-off-by: Vinod Koul <vkoul@kernel.org>
---
 drivers/crypto/qcom-rng.c | 37 +++++++++++++++++++++++++++++++++----
 1 file changed, 33 insertions(+), 4 deletions(-)

diff --git a/drivers/crypto/qcom-rng.c b/drivers/crypto/qcom-rng.c
index fdbbcac7bcb8..bc0131d130d6 100644
--- a/drivers/crypto/qcom-rng.c
+++ b/drivers/crypto/qcom-rng.c
@@ -4,6 +4,7 @@
 // Based on msm-rng.c and downstream driver
 
 #include <crypto/internal/rng.h>
+#include <linux/acpi.h>
 #include <linux/clk.h>
 #include <linux/crypto.h>
 #include <linux/module.h>
@@ -154,6 +155,7 @@ static int qcom_rng_probe(struct platform_device *pdev)
 {
 	struct resource *res;
 	struct qcom_rng *rng;
+	u32 val;
 	int ret;
 
 	rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
@@ -168,11 +170,27 @@ static int qcom_rng_probe(struct platform_device *pdev)
 	if (IS_ERR(rng->base))
 		return PTR_ERR(rng->base);
 
-	rng->clk = devm_clk_get(&pdev->dev, "core");
-	if (IS_ERR(rng->clk))
-		return PTR_ERR(rng->clk);
 
-	rng->skip_init = (unsigned long)of_device_get_match_data(&pdev->dev);
+	/*
+	 * ACPI systems have v2 hardware. The clocks are always enabled,
+	 * the PRNG register space is read-only and the PRNG should
+	 * already be enabled.
+	 */
+	if (has_acpi_companion(&pdev->dev)) {
+		val = readl(rng->base + PRNG_CONFIG);
+		if (!(val & PRNG_CONFIG_HW_ENABLE)) {
+			dev_err(&pdev->dev, "device is not enabled\n");
+			return -ENODEV;
+		}
+		rng->skip_init = 1;
+	} else {
+		rng->clk = devm_clk_get(&pdev->dev, "core");
+		if (IS_ERR(rng->clk))
+			return PTR_ERR(rng->clk);
+
+		rng->skip_init =
+			(unsigned long)of_device_get_match_data(&pdev->dev);
+	}
 
 	qcom_rng_dev = rng;
 	ret = crypto_register_rng(&qcom_rng_alg);
@@ -193,6 +211,16 @@ static int qcom_rng_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#if IS_ENABLED(CONFIG_ACPI)
+static const struct acpi_device_id qcom_rng_acpi_match[] = {
+	{
+		.id = "QCOM8160",
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(acpi, msm_rng_acpi_match);
+#endif
+
 static const struct of_device_id qcom_rng_of_match[] = {
 	{ .compatible = "qcom,prng", .data = (void *)0},
 	{ .compatible = "qcom,prng-ee", .data = (void *)1},
@@ -206,6 +234,7 @@ static struct platform_driver qcom_rng_driver = {
 	.driver = {
 		.name = KBUILD_MODNAME,
 		.of_match_table = of_match_ptr(qcom_rng_of_match),
+		.acpi_match_table = ACPI_PTR(qcom_rng_acpi_match),
 	}
 };
 module_platform_driver(qcom_rng_driver);
-- 
2.14.4