serial: 8250_of: manage bus clock in suspend/resume

Save the bus clock pointer in the of_serial_info structure, and use
that to disable the bus clock on suspend and re-enable it on resume.

Signed-off-by: Alex Elder <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Reviewed-by: Yixun Lan <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/8250/8250_of.c

···
 
 struct of_serial_info {
 	struct clk *clk;
+	struct clk *bus_clk;
 	struct reset_control *rst;
 	int type;
 	int line;
···
 			goto err_pmruntime;
 		}
 
+		info->bus_clk = bus_clk;
 		port->uartclk = clk_get_rate(info->clk);
 	}
 	/* If current-speed was set, then try not to change it. */
···
 	if (!uart_console(port) || console_suspend_enabled) {
 		pm_runtime_put_sync(dev);
 		clk_disable_unprepare(info->clk);
+		clk_disable_unprepare(info->bus_clk);
 	}
 	return 0;
 }
···
 
 	if (!uart_console(port) || console_suspend_enabled) {
 		pm_runtime_get_sync(dev);
+		clk_prepare_enable(info->bus_clk);
 		clk_prepare_enable(info->clk);
 	}