[PATCH V2] spi: spi-cadence-quadspi: add runtime pm support

[Dhruva Gole <d-gole@xxxxxx>]

Add runtime pm support to cadence-qspi driver, this allows the driver to
suspend whenever it's is not actively being used thus reducing active
power consumed by the system.

Also, with the use of devm_pm_runtime_enable we no longer need the
fallback probe_pm_failed that used to pm_runtime_disable

Co-developed-by: Apurva Nandan <a-nandan@xxxxxx>
Signed-off-by: Apurva Nandan <a-nandan@xxxxxx>
Signed-off-by: Dhruva Gole <d-gole@xxxxxx>
---

Previous patch was marked RFT, and can be found here [0].
Tested [1] this patch on a TI SK-AM62 EVM having an OSPI NOR flash on board.

Changelog:
* Drop the DT patch as it had some comments that I am planning to
address at a later point.
* Add a ret val check for the pm_runtime_resume_and_get function call in
the exec_mem_op in case it reports any failures.

[0] https://lore.kernel.org/all/20230818103750.516309-3-d-gole@xxxxxx/
[1] https://gist.github.com/DhruvaG2000/7728ec09ae49c8c0d44d8e99de6795d5

Cc: Sai Krishna Potthuri <lakshmi.sai.krishna.potthuri@xxxxxxxxxx>
Cc: Ian Abbott <abbotti@xxxxxxxxx>
Cc: William Qiu <william.qiu@xxxxxxxxxxxxxxxx>
Cc: Brad Larson <blarson@xxxxxxx>
Cc: Pratyush Yadav <ptyadav@xxxxxxxxx>
Cc: Vignesh Raghavendra <vigneshr@xxxxxx>
Cc: Vibhore Vardhan <vibhore@xxxxxx>

 drivers/spi/spi-cadence-quadspi.c | 42 ++++++++++++++++++++++++-------
 1 file changed, 33 insertions(+), 9 deletions(-)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index b50db71ac4cc..4828da4587c5 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -116,6 +116,9 @@ struct cqspi_driver_platdata {
 #define CQSPI_TIMEOUT_MS			500
 #define CQSPI_READ_TIMEOUT_MS			10
 
+/* Runtime_pm autosuspend delay */
+#define CQSPI_AUTOSUSPEND_TIMEOUT		2000
+
 #define CQSPI_DUMMY_CLKS_PER_BYTE		8
 #define CQSPI_DUMMY_BYTES_MAX			4
 #define CQSPI_DUMMY_CLKS_MAX			31
@@ -1407,8 +1410,20 @@ static int cqspi_mem_process(struct spi_mem *mem, const struct spi_mem_op *op)
 static int cqspi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
 {
 	int ret;
+	struct cqspi_st *cqspi = spi_master_get_devdata(mem->spi->master);
+	struct device *dev = &cqspi->pdev->dev;
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret) {
+		dev_err(&mem->spi->dev, "resume failed with %d\n", ret);
+		return ret;
+	}
 
 	ret = cqspi_mem_process(mem, op);
+
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put_autosuspend(dev);
+
 	if (ret)
 		dev_err(&mem->spi->dev, "operation failed with %d\n", ret);
 
@@ -1753,10 +1768,10 @@ static int cqspi_probe(struct platform_device *pdev)
 	if (irq < 0)
 		return -ENXIO;
 
-	pm_runtime_enable(dev);
-	ret = pm_runtime_resume_and_get(dev);
-	if (ret < 0)
-		goto probe_pm_failed;
+	ret = pm_runtime_set_active(dev);
+	if (ret)
+		return ret;
+
 
 	ret = clk_prepare_enable(cqspi->clk);
 	if (ret) {
@@ -1862,21 +1877,29 @@ static int cqspi_probe(struct platform_device *pdev)
 			goto probe_setup_failed;
 	}
 
+	ret = devm_pm_runtime_enable(dev);
+	if (ret)
+		return ret;
+
+	pm_runtime_set_autosuspend_delay(dev, CQSPI_AUTOSUSPEND_TIMEOUT);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_get_noresume(dev);
+
 	ret = spi_register_controller(host);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to register SPI ctlr %d\n", ret);
 		goto probe_setup_failed;
 	}
 
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put_autosuspend(dev);
+
 	return 0;
 probe_setup_failed:
 	cqspi_controller_enable(cqspi, 0);
 probe_reset_failed:
 	clk_disable_unprepare(cqspi->clk);
 probe_clk_failed:
-	pm_runtime_put_sync(dev);
-probe_pm_failed:
-	pm_runtime_disable(dev);
 	return ret;
 }
 
@@ -1928,7 +1951,8 @@ static int cqspi_resume(struct device *dev)
 	return spi_controller_resume(host);
 }
 
-static DEFINE_SIMPLE_DEV_PM_OPS(cqspi_dev_pm_ops, cqspi_suspend, cqspi_resume);
+static DEFINE_RUNTIME_DEV_PM_OPS(cqspi_dev_pm_ops, cqspi_suspend,
+				 cqspi_resume, NULL);
 
 static const struct cqspi_driver_platdata cdns_qspi = {
 	.quirks = CQSPI_DISABLE_DAC_MODE,
@@ -2012,7 +2036,7 @@ static struct platform_driver cqspi_platform_driver = {
 	.remove_new = cqspi_remove,
 	.driver = {
 		.name = CQSPI_NAME,
-		.pm = &cqspi_dev_pm_ops,
+		.pm = pm_ptr(&cqspi_dev_pm_ops),
 		.of_match_table = cqspi_dt_ids,
 	},
 };
-- 
2.34.1