tty: serial: qcom_geni_serial: Use OPP API to set clk/perf state

geni serial needs to express a perforamnce state requirement on CX
powerdomain depending on the frequency of the clock rates.
Use OPP table from DT to register with OPP framework and use
dev_pm_opp_set_rate() to set the clk/perf state.

Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Akash Asthana <akashast@codeaurora.org>
Cc: linux-serial@vger.kernel.org
Link: https://lore.kernel.org/r/1588507469-31889-2-git-send-email-rnayak@codeaurora.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/qcom_geni_serial.c

@@ -9,6 +9,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/pm_opp.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/pm_wakeirq.h>
@@ -961,7 +962,7 @@ static void qcom_geni_serial_set_termios(struct uart_port *uport,
 		goto out_restart_rx;
 
 	uport->uartclk = clk_rate;
-	clk_set_rate(port->se.clk, clk_rate);
+	dev_pm_opp_set_rate(uport->dev, clk_rate);
 	ser_clk_cfg = SER_CLK_EN;
 	ser_clk_cfg |= clk_div << CLK_DIV_SHFT;
 
@@ -1198,8 +1199,11 @@ static void qcom_geni_serial_pm(struct uart_port *uport,
 	if (new_state == UART_PM_STATE_ON && old_state == UART_PM_STATE_OFF)
 		geni_se_resources_on(&port->se);
 	else if (new_state == UART_PM_STATE_OFF &&
-			old_state == UART_PM_STATE_ON)
+			old_state == UART_PM_STATE_ON) {
+		/* Drop the performance state vote */
+		dev_pm_opp_set_rate(uport->dev, 0);
 		geni_se_resources_off(&port->se);
+	}
 }
 
 static const struct uart_ops qcom_geni_console_pops = {
@@ -1318,21 +1322,33 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
 	if (of_property_read_bool(pdev->dev.of_node, "cts-rts-swap"))
 		port->cts_rts_swap = true;
 
+	port->se.opp_table = dev_pm_opp_set_clkname(&pdev->dev, "se");
+	if (IS_ERR(port->se.opp_table))
+		return PTR_ERR(port->se.opp_table);
+	/* OPP table is optional */
+	ret = dev_pm_opp_of_add_table(&pdev->dev);
+	if (!ret) {
+		port->se.has_opp_table = true;
+	} else if (ret != -ENODEV) {
+		dev_err(&pdev->dev, "invalid OPP table in device tree\n");
+		return ret;
+	}
+
 	uport->private_data = drv;
 	platform_set_drvdata(pdev, port);
 	port->handle_rx = console ? handle_rx_console : handle_rx_uart;
 
 	ret = uart_add_one_port(drv, uport);
 	if (ret)
-		return ret;
+		goto err;
 
 	irq_set_status_flags(uport->irq, IRQ_NOAUTOEN);
 	ret = devm_request_irq(uport->dev, uport->irq, qcom_geni_serial_isr,
 			IRQF_TRIGGER_HIGH, port->name, uport);
 	if (ret) {
 		dev_err(uport->dev, "Failed to get IRQ ret %d\n", ret);
 		uart_remove_one_port(drv, uport);
-		return ret;
+		goto err;
 	}
 
 	/*
@@ -1349,18 +1365,26 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
 		if (ret) {
 			device_init_wakeup(&pdev->dev, false);
 			uart_remove_one_port(drv, uport);
-			return ret;
+			goto err;
 		}
 	}
 
 	return 0;
+err:
+	if (port->se.has_opp_table)
+		dev_pm_opp_of_remove_table(&pdev->dev);
+	dev_pm_opp_put_clkname(port->se.opp_table);
+	return ret;
 }
 
 static int qcom_geni_serial_remove(struct platform_device *pdev)
 {
 	struct qcom_geni_serial_port *port = platform_get_drvdata(pdev);
 	struct uart_driver *drv = port->uport.private_data;
 
+	if (port->se.has_opp_table)
+		dev_pm_opp_of_remove_table(&pdev->dev);
+	dev_pm_opp_put_clkname(port->se.opp_table);
 	dev_pm_clear_wake_irq(&pdev->dev);
 	device_init_wakeup(&pdev->dev, false);
 	uart_remove_one_port(drv, &port->uport);

include/linux/qcom-geni-se.h

@@ -33,6 +33,8 @@ struct clk;
  * @clk:		Handle to the core serial engine clock
  * @num_clk_levels:	Number of valid clock levels in clk_perf_tbl
  * @clk_perf_tbl:	Table of clock frequency input to serial engine clock
+ * @opp_table:		Pointer to the OPP table
+ * @has_opp_table:	Specifies if the SE has an OPP table
  */
 struct geni_se {
 	void __iomem *base;
@@ -41,6 +43,8 @@ struct geni_se {
 	struct clk *clk;
 	unsigned int num_clk_levels;
 	unsigned long *clk_perf_tbl;
+	struct opp_table *opp_table;
+	bool has_opp_table;
 };
 
 /* Common SE registers */