[PATCH V6 2/7] soc: qcom-geni-se: Add interconnect support to fix earlycon crash

[Akash Asthana <akashast@xxxxxxxxxxxxxx>]

QUP core clock is shared among all the SE drivers present on particular
QUP wrapper, the system will reset(unclocked access) if earlycon used after
QUP core clock is put to 0 from other SE drivers before real console comes
up.

As earlycon can't vote for it's QUP core need, to fix this add ICC
support to common/QUP wrapper driver and put vote for QUP core from
probe on behalf of earlycon and remove vote during earlycon exit call.

Signed-off-by: Akash Asthana <akashast@xxxxxxxxxxxxxx>
Reported-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
---
Change in V3:
 - Add geni_remove_earlycon_icc_vote API that will be used by earlycon
   exit function to remove ICC vote for earlyconsole.
 - Remove suspend/resume hook for geni-se driver as we are no longer
   removing earlyconsole ICC vote from system suspend, we are removing
   from earlycon exit.

Change in V4:
 - As per Matthias comment make 'earlycon_wrapper' as static structure.

Changes in V5:
 - Vote for core path only after checking whether "qcom_geni" earlycon is
   actually present or not by traversing over structure "console_drivers".

Changes in V6:
 - As per Matthias's comment removed NULL check for console_drivers global
   struct, added NULL check for earlycon_wrapper in _remove_earlycon_icc_vote
   API
 - Addressed nitpicks from Andy.

 drivers/soc/qcom/qcom-geni-se.c       | 68 +++++++++++++++++++++++++++++++++++
 drivers/tty/serial/qcom_geni_serial.c |  7 ++++
 include/linux/qcom-geni-se.h          |  2 ++
 3 files changed, 77 insertions(+)

diff --git a/drivers/soc/qcom/qcom-geni-se.c b/drivers/soc/qcom/qcom-geni-se.c
index 0b2526d..ac16bb1 100644
--- a/drivers/soc/qcom/qcom-geni-se.c
+++ b/drivers/soc/qcom/qcom-geni-se.c
@@ -3,6 +3,7 @@
 
 #include <linux/acpi.h>
 #include <linux/clk.h>
+#include <linux/console.h>
 #include <linux/slab.h>
 #include <linux/dma-mapping.h>
 #include <linux/io.h>
@@ -90,11 +91,14 @@ struct geni_wrapper {
 	struct device *dev;
 	void __iomem *base;
 	struct clk_bulk_data ahb_clks[NUM_AHB_CLKS];
+	struct geni_icc_path to_core;
 };
 
 static const char * const icc_path_names[] = {"qup-core", "qup-config",
 						"qup-memory"};
 
+static struct geni_wrapper *earlycon_wrapper;
+
 #define QUP_HW_VER_REG			0x4
 
 /* Common SE registers */
@@ -812,11 +816,38 @@ int geni_icc_disable(struct geni_se *se)
 }
 EXPORT_SYMBOL(geni_icc_disable);
 
+void geni_remove_earlycon_icc_vote(void)
+{
+	struct geni_wrapper *wrapper;
+	struct device_node *parent;
+	struct device_node *child;
+
+	if (!earlycon_wrapper)
+		return;
+
+	wrapper = earlycon_wrapper;
+	parent = of_get_next_parent(wrapper->dev->of_node);
+	for_each_child_of_node(parent, child) {
+		if (!of_device_is_compatible(child, "qcom,geni-se-qup"))
+			continue;
+		wrapper = platform_get_drvdata(of_find_device_by_node(child));
+		icc_put(wrapper->to_core.path);
+		wrapper->to_core.path = NULL;
+
+	}
+	of_node_put(parent);
+
+	earlycon_wrapper = NULL;
+}
+EXPORT_SYMBOL(geni_remove_earlycon_icc_vote);
+
 static int geni_se_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct resource *res;
 	struct geni_wrapper *wrapper;
+	struct console __maybe_unused *bcon;
+	bool __maybe_unused has_earlycon = false;
 	int ret;
 
 	wrapper = devm_kzalloc(dev, sizeof(*wrapper), GFP_KERNEL);
@@ -839,6 +870,43 @@ static int geni_se_probe(struct platform_device *pdev)
 		}
 	}
 
+#ifdef CONFIG_SERIAL_EARLYCON
+	for_each_console(bcon) {
+		if (!strcmp(bcon->name, "qcom_geni")) {
+			has_earlycon = true;
+			break;
+		}
+	}
+	if (!has_earlycon)
+		goto exit;
+
+	wrapper->to_core.path = devm_of_icc_get(dev, "qup-core");
+	if (IS_ERR(wrapper->to_core.path))
+		return PTR_ERR(wrapper->to_core.path);
+	/*
+	 * Put minmal BW request on core clocks on behalf of early console.
+	 * The vote will be removed earlycon exit function.
+	 *
+	 * Note: We are putting vote on each QUP wrapper instead only to which
+	 * earlycon is connected because QUP core clock of different wrapper
+	 * share same voltage domain. If core1 is put to 0, then core2 will
+	 * also run at 0, if not voted. Default ICC vote will be removed ASA
+	 * we touch any of the core clock.
+	 * core1 = core2 = max(core1, core2)
+	 */
+	ret = icc_set_bw(wrapper->to_core.path, GENI_DEFAULT_BW,
+				GENI_DEFAULT_BW);
+	if (ret) {
+		dev_err(&pdev->dev, "%s: ICC BW voting failed for core :%d\n",
+			__func__, ret);
+		return ret;
+	}
+
+	if (of_get_compatible_child(pdev->dev.of_node, "qcom,geni-debug-uart"))
+		earlycon_wrapper = wrapper;
+	of_node_put(pdev->dev.of_node);
+#endif
+exit:
 	dev_set_drvdata(dev, wrapper);
 	dev_dbg(dev, "GENI SE Driver probed\n");
 	return devm_of_platform_populate(dev);
diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 6119090..8c5d97c 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -1090,6 +1090,12 @@ static void qcom_geni_serial_earlycon_write(struct console *con,
 	__qcom_geni_serial_console_write(&dev->port, s, n);
 }
 
+static int qcom_geni_serial_earlycon_exit(struct console *con)
+{
+	geni_remove_earlycon_icc_vote();
+	return 0;
+}
+
 static int __init qcom_geni_serial_earlycon_setup(struct earlycon_device *dev,
 								const char *opt)
 {
@@ -1135,6 +1141,7 @@ static int __init qcom_geni_serial_earlycon_setup(struct earlycon_device *dev,
 	writel(stop_bit_len, uport->membase + SE_UART_TX_STOP_BIT_LEN);
 
 	dev->con->write = qcom_geni_serial_earlycon_write;
+	dev->con->exit = qcom_geni_serial_earlycon_exit;
 	dev->con->setup = NULL;
 	return 0;
 }
diff --git a/include/linux/qcom-geni-se.h b/include/linux/qcom-geni-se.h
index 7afa08d..51e9e9b 100644
--- a/include/linux/qcom-geni-se.h
+++ b/include/linux/qcom-geni-se.h
@@ -458,5 +458,7 @@ void geni_icc_bw_init(struct geni_icc_path *icc_paths, unsigned int avg_bw,
 int geni_icc_enable(struct geni_se *se);
 
 int geni_icc_disable(struct geni_se *se);
+
+void geni_remove_earlycon_icc_vote(void);
 #endif
 #endif
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,\na Linux Foundation Collaborative Project