[PATCH V7 6/7] spi: spi-qcom-qspi: Add interconnect support

[Akash Asthana <akashast@xxxxxxxxxxxxxx>]

Get the interconnect paths for QSPI device and vote according to the
current bus speed of the driver.

Signed-off-by: Akash Asthana <akashast@xxxxxxxxxxxxxx>
---
Changes in V2:
 - As per Bjorn's comment, introduced and using devm_of_icc_get API for getting
   path handle
 - As per Matthias comment, added error handling for icc_set_bw call

Changes in V3:
 - No Change.

Changes in V4:
 - As per Mark's comment move peak_bw guess as twice of avg_bw if
   nothing mentioned explicitly to ICC core.

Changes in V5:
 - Add icc_enable/disable to power on/off call.
 - Save some non-zero avg/peak value to ICC core by calling geni_icc_set_bw
   from probe so that when resume/icc_enable is called NOC are running at
   some non-zero value.

Changes in V6:
 - As per Matthias's comment made print statement consistent across driver

Changes in V7:
 - As per Matthias's comment removed usage of peak_bw variable because we don't
   have explicit peak requirement, we were voting peak = avg and this can be
   tracked using single variable for avg bw.
 - As per Matthias's comment improved print log.

 drivers/spi/spi-qcom-qspi.c | 57 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 56 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-qcom-qspi.c b/drivers/spi/spi-qcom-qspi.c
index 3c4f83b..092ac27 100644
--- a/drivers/spi/spi-qcom-qspi.c
+++ b/drivers/spi/spi-qcom-qspi.c
@@ -2,6 +2,7 @@
 // Copyright (c) 2017-2018, The Linux foundation. All rights reserved.
 
 #include <linux/clk.h>
+#include <linux/interconnect.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/module.h>
@@ -139,7 +140,9 @@ struct qcom_qspi {
 	struct device *dev;
 	struct clk_bulk_data *clks;
 	struct qspi_xfer xfer;
-	/* Lock to protect xfer and IRQ accessed registers */
+	struct icc_path *icc_path_cpu_to_qspi;
+	unsigned int avg_bw_cpu;
+	/* Lock to protect data accessed by IRQs */
 	spinlock_t lock;
 };
 
@@ -241,6 +244,19 @@ static int qcom_qspi_transfer_one(struct spi_master *master,
 		return ret;
 	}
 
+	/*
+	 * Set BW quota for CPU as driver supports FIFO mode only.
+	 * We don't have explicit peak requirement so keep it equal to avg_bw.
+	 */
+	ctrl->avg_bw_cpu = Bps_to_icc(speed_hz);
+	ret = icc_set_bw(ctrl->icc_path_cpu_to_qspi, ctrl->avg_bw_cpu,
+		ctrl->avg_bw_cpu);
+	if (ret) {
+		dev_err(ctrl->dev, "%s: ICC BW voting failed for cpu: %d\n",
+			__func__, ret);
+		return ret;
+	}
+
 	spin_lock_irqsave(&ctrl->lock, flags);
 
 	/* We are half duplex, so either rx or tx will be set */
@@ -458,6 +474,29 @@ static int qcom_qspi_probe(struct platform_device *pdev)
 	if (ret)
 		goto exit_probe_master_put;
 
+	ctrl->icc_path_cpu_to_qspi = devm_of_icc_get(dev, "qspi-config");
+	if (IS_ERR(ctrl->icc_path_cpu_to_qspi)) {
+		ret = PTR_ERR(ctrl->icc_path_cpu_to_qspi);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "Failed to get cpu path: %d\n", ret);
+		goto exit_probe_master_put;
+	}
+	/* Set BW vote for register access */
+	ret = icc_set_bw(ctrl->icc_path_cpu_to_qspi, Bps_to_icc(1000),
+				Bps_to_icc(1000));
+	if (ret) {
+		dev_err(ctrl->dev, "%s: ICC BW voting failed for cpu: %d\n",
+				__func__, ret);
+		goto exit_probe_master_put;
+	}
+
+	ret = icc_disable(ctrl->icc_path_cpu_to_qspi);
+	if (ret) {
+		dev_err(ctrl->dev, "%s: ICC disable failed for cpu: %d\n",
+				__func__, ret);
+		goto exit_probe_master_put;
+	}
+
 	ret = platform_get_irq(pdev, 0);
 	if (ret < 0)
 		goto exit_probe_master_put;
@@ -511,9 +550,17 @@ static int __maybe_unused qcom_qspi_runtime_suspend(struct device *dev)
 {
 	struct spi_master *master = dev_get_drvdata(dev);
 	struct qcom_qspi *ctrl = spi_master_get_devdata(master);
+	int ret;
 
 	clk_bulk_disable_unprepare(QSPI_NUM_CLKS, ctrl->clks);
 
+	ret = icc_disable(ctrl->icc_path_cpu_to_qspi);
+	if (ret) {
+		dev_err_ratelimited(ctrl->dev, "%s: ICC disable failed for cpu: %d\n",
+			__func__, ret);
+		return ret;
+	}
+
 	return 0;
 }
 
@@ -521,6 +568,14 @@ static int __maybe_unused qcom_qspi_runtime_resume(struct device *dev)
 {
 	struct spi_master *master = dev_get_drvdata(dev);
 	struct qcom_qspi *ctrl = spi_master_get_devdata(master);
+	int ret;
+
+	ret = icc_enable(ctrl->icc_path_cpu_to_qspi);
+	if (ret) {
+		dev_err_ratelimited(ctrl->dev, "%s: ICC enable failed for cpu: %d\n",
+			__func__, ret);
+		return ret;
+	}
 
 	return clk_bulk_prepare_enable(QSPI_NUM_CLKS, ctrl->clks);
 }
-- 
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