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@xxxxxxxxxxxxxx>
---
drivers/char/hw_random/msm-rng.c | 40 ++++++++++++++++++++++++++++++++++------
1 file changed, 34 insertions(+), 6 deletions(-)
diff --git a/drivers/char/hw_random/msm-rng.c b/drivers/char/hw_random/msm-rng.c
index 44580588b938..f34713d23d77 100644
--- a/drivers/char/hw_random/msm-rng.c
+++ b/drivers/char/hw_random/msm-rng.c
@@ -20,6 +20,7 @@
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
+#include <linux/acpi.h>
/* Device specific register offsets */
#define PRNG_DATA_OUT 0x0000
@@ -186,16 +187,32 @@ static int msm_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->hwrng.name = KBUILD_MODNAME;
- rng->hwrng.init = msm_rng_init;
- rng->hwrng.cleanup = msm_rng_cleanup;
rng->hwrng.read = msm_rng_read;
spin_lock_init(&rng->lock);
+ /*
+ * 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)) {
+ u32 val;
+
+ val = readl(rng->base + PRNG_CONFIG);
+ if (!(val & PRNG_CONFIG_HW_ENABLE)) {
+ dev_err(&pdev->dev, "device is not enabled\n");
+ return -ENODEV;
+ }
+ } else {
+ rng->clk = devm_clk_get(&pdev->dev, "core");
+ if (IS_ERR(rng->clk))
+ return PTR_ERR(rng->clk);
+
+ rng->hwrng.init = msm_rng_init;
+ rng->hwrng.cleanup = msm_rng_cleanup;
+ }
+
ret = devm_hwrng_register(&pdev->dev, &rng->hwrng);
if (ret) {
dev_err(&pdev->dev, "failed to register hwrng\n");
@@ -211,11 +228,22 @@ static int msm_rng_probe(struct platform_device *pdev)
};
MODULE_DEVICE_TABLE(of, msm_rng_of_match);
+#if IS_ENABLED(CONFIG_ACPI)
+static const struct acpi_device_id msm_rng_acpi_match[] = {
+ {
+ .id = "QCOM8160", /* v2 PRNG */
+ },
+ {}
+};
+MODULE_DEVICE_TABLE(acpi, msm_rng_acpi_match);
+#endif
+
static struct platform_driver msm_rng_driver = {
.probe = msm_rng_probe,
.driver = {
.name = KBUILD_MODNAME,
.of_match_table = of_match_ptr(msm_rng_of_match),
+ .acpi_match_table = ACPI_PTR(msm_rng_acpi_match),
}
};
module_platform_driver(msm_rng_driver);
--
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
Technologies, Inc. Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.
