linux-kernel - [PATCH v2 4/4] i2c: i2c-qcom-geni: Enable i2c controller sharing between two subsystems

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Message-Id: <20240906191438.4104329-5-quic_msavaliy@quicinc.com>
Date: Sat,  7 Sep 2024 00:44:38 +0530
From: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
To: konrad.dybcio@...aro.org, andersson@...nel.org, andi.shyti@...nel.org,
        linux-arm-msm@...r.kernel.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
        conor+dt@...nel.org, agross@...nel.org, devicetree@...r.kernel.org,
        vkoul@...nel.org, linux@...blig.org, dan.carpenter@...aro.org,
        Frank.Li@....com, konradybcio@...nel.org
Cc: quic_vdadhani@...cinc.com,
        Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
Subject: [PATCH v2 4/4] i2c: i2c-qcom-geni: Enable i2c controller sharing between two subsystems

Add support to share I2C SE by two Subsystems in a mutually exclusive way.
Use  "qcom,shared-se" flag in a particular i2c instance node if the
usecase requires i2c controller to be shared.

I2C driver just need to mark first_msg and last_msg flag to help indicate
GPI driver to  take lock and unlock TRE there by protecting from concurrent
access from other EE or Subsystem.

gpi_create_i2c_tre() function at gpi.c will take care of adding Lock and
Unlock TRE for the respective transfer operations.

Since the GPIOs are also shared for the i2c bus between two SS, do not
touch GPIO configuration during runtime suspend and only turn off the
clocks. This will allow other SS to continue to transfer the data
without any disturbance over the IO lines.

Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
---
 drivers/i2c/busses/i2c-qcom-geni.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
index eebb0cbb6ca4..ee2e431601a6 100644
--- a/drivers/i2c/busses/i2c-qcom-geni.c
+++ b/drivers/i2c/busses/i2c-qcom-geni.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (c) 2017-2018, The Linux Foundation. All rights reserved.
+// Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.
 
 #include <linux/acpi.h>
 #include <linux/clk.h>
@@ -99,6 +100,7 @@ struct geni_i2c_dev {
 	struct dma_chan *rx_c;
 	bool gpi_mode;
 	bool abort_done;
+	bool is_shared;
 };
 
 struct geni_i2c_desc {
@@ -602,6 +604,7 @@ static int geni_i2c_gpi_xfer(struct geni_i2c_dev *gi2c, struct i2c_msg msgs[], i
 	peripheral.clk_div = itr->clk_div;
 	peripheral.set_config = 1;
 	peripheral.multi_msg = false;
+	peripheral.shared_se = gi2c->is_shared;
 
 	for (i = 0; i < num; i++) {
 		gi2c->cur = &msgs[i];
@@ -612,6 +615,8 @@ static int geni_i2c_gpi_xfer(struct geni_i2c_dev *gi2c, struct i2c_msg msgs[], i
 		if (i < num - 1)
 			peripheral.stretch = 1;
 
+		peripheral.first_msg = (i == 0);
+		peripheral.last_msg = (i == num - 1);
 		peripheral.addr = msgs[i].addr;
 
 		ret =  geni_i2c_gpi(gi2c, &msgs[i], &config,
@@ -631,8 +636,11 @@ static int geni_i2c_gpi_xfer(struct geni_i2c_dev *gi2c, struct i2c_msg msgs[], i
 		dma_async_issue_pending(gi2c->tx_c);
 
 		time_left = wait_for_completion_timeout(&gi2c->done, XFER_TIMEOUT);
-		if (!time_left)
+		if (!time_left) {
+			dev_err(gi2c->se.dev, "I2C timeout gpi flags:%d addr:0x%x\n",
+						gi2c->cur->flags, gi2c->cur->addr);
 			gi2c->err = -ETIMEDOUT;
+		}
 
 		if (gi2c->err) {
 			ret = gi2c->err;
@@ -800,6 +808,11 @@ static int geni_i2c_probe(struct platform_device *pdev)
 		gi2c->clk_freq_out = KHZ(100);
 	}
 
+	if (of_property_read_bool(pdev->dev.of_node, "qcom,shared-se")) {
+		gi2c->is_shared = true;
+		dev_dbg(&pdev->dev, "Shared SE Usecase\n");
+	}
+
 	if (has_acpi_companion(dev))
 		ACPI_COMPANION_SET(&gi2c->adap.dev, ACPI_COMPANION(dev));
 
@@ -962,14 +975,16 @@ static int __maybe_unused geni_i2c_runtime_suspend(struct device *dev)
 	struct geni_i2c_dev *gi2c = dev_get_drvdata(dev);
 
 	disable_irq(gi2c->irq);
-	ret = geni_se_resources_off(&gi2c->se);
-	if (ret) {
-		enable_irq(gi2c->irq);
-		return ret;
-
+	if (gi2c->is_shared) {
+		geni_se_clks_off(&gi2c->se);
 	} else {
-		gi2c->suspended = 1;
+		ret = geni_se_resources_off(&gi2c->se);
+		if (ret) {
+			enable_irq(gi2c->irq);
+			return ret;
+		}
 	}
+	gi2c->suspended = 1;
 
 	clk_disable_unprepare(gi2c->core_clk);
 
-- 
2.25.1