2014-08-08 14:28 GMT+02:00 Tobias Klauser [off-list ref]:

On 2014-08-08 at 13:32:03 +0200, Matthias Brugger [off-list ref] wrote:

quoted

This patch adds support for the UART block found on Mediatek SoCs.
The device has a highspeed register which influences the calcualtion of the
divisor. The chip lacks support for some baudrates. When requested, we set the
divisor to the next smaller baudrate and adjust the c_cflag accordingly.

Signed-off-by: Matthias Brugger <redacted>
---
 drivers/tty/serial/8250/8250_mtk.c |  296 ++++++++++++++++++++++++++++++++++++
 drivers/tty/serial/8250/Kconfig    |    7 +
 drivers/tty/serial/8250/Makefile   |    1 +
 3 files changed, 304 insertions(+)
 create mode 100644 drivers/tty/serial/8250/8250_mtk.c

diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
new file mode 100644
index 0000000..d63080b
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_mtk.c

@@ -0,0 +1,296 @@

[...]

quoted

+static int mtk8250_probe(struct platform_device *pdev)
+{
+     struct uart_8250_port uart = {};
+     struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+     struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+     struct mtk8250_data *data;
+     int err;
+
+     if (!regs || !irq) {
+             dev_err(&pdev->dev, "no registers/irq defined\n");
+             return -EINVAL;
+     }
+
+     spin_lock_init(&uart.port.lock);
+     uart.port.mapbase = regs->start;
+     uart.port.irq = irq->start;
+     uart.port.pm = mtk8250_do_pm;
+     uart.port.type = PORT_16550;
+     uart.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT;
+     uart.port.dev = &pdev->dev;
+
+     uart.port.membase = devm_ioremap(&pdev->dev, regs->start,
+                                      resource_size(regs));
+     if (!uart.port.membase)
+             return -ENOMEM;

You can use devm_ioremap_resource here and get rid of the check for
!regs above, since devm_ioremap_resource already does that.

        regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);

        ...

        uart.port.membase = devm_ioremap_resource(&pdev->dev, regs);
        if (IS_ERR(uart.port.membase))
                return PTR_ERR(uart.port.membase);

devm_ioremap_resource creates a busy resource region in the
iomem_resource. This leads the UART to silently fail.
I suppose that's why 8250_dw.c uses devm_ioremap instead of
devm_ioremap_resource. The 8250_dw has the same issue.

Thanks,
Matthias

quoted

+
+     data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+     if (!data)
+             return -ENOMEM;

I'd suggest to move this kzalloc and the ioremap before the uart.port
initialization part above, so you can error out early in case of any
failure.

quoted

+
+     uart.port.iotype = UPIO_MEM32;
+     uart.port.regshift = 2;
+     uart.port.private_data = data;
+     uart.port.set_termios = mtk8250_set_termios;
+
+     if (pdev->dev.of_node) {
+             err = mtk8250_probe_of(&uart.port, data);
+             if (err)
+                     return err;
+     } else
+             return -ENODEV;

This could also be moved up, directly below devm_kzalloc.

quoted

+
+     /* Disable Rate Fix function */
+     writel(0x0, uart.port.membase +
+                     (MTK_UART_RATE_FIX << uart.port.regshift));
+
+     data->line = serial8250_register_8250_port(&uart);
+     if (data->line < 0)
+             return data->line;
+
+     platform_set_drvdata(pdev, data);
+
+     pm_runtime_set_active(&pdev->dev);
+     pm_runtime_enable(&pdev->dev);
+
+     return 0;
+}
+
+static int mtk8250_remove(struct platform_device *pdev)
+{
+     struct mtk8250_data *data = platform_get_drvdata(pdev);
+
+     pm_runtime_get_sync(&pdev->dev);
+
+     serial8250_unregister_port(data->line);
+     if (!IS_ERR(data->clk)) {
+             clk_disable_unprepare(data->clk);
+             clk_put(data->clk);
+     }
+
+     pm_runtime_disable(&pdev->dev);
+     pm_runtime_put_noidle(&pdev->dev);
+     return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int mtk8250_suspend(struct device *dev)
+{
+     struct mtk8250_data *data = dev_get_drvdata(dev);
+
+     serial8250_suspend_port(data->line);
+
+     return 0;
+}
+
+static int mtk8250_resume(struct device *dev)
+{
+     struct mtk8250_data *data = dev_get_drvdata(dev);
+
+     serial8250_resume_port(data->line);
+
+     return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+#ifdef CONFIG_PM_RUNTIME
+static int mtk8250_runtime_suspend(struct device *dev)
+{
+     struct mtk8250_data *data = dev_get_drvdata(dev);
+
+     if (!IS_ERR(data->clk))
+             clk_disable_unprepare(data->clk);
+
+     return 0;
+}
+
+static int mtk8250_runtime_resume(struct device *dev)
+{
+     struct mtk8250_data *data = dev_get_drvdata(dev);
+
+     if (!IS_ERR(data->clk))
+             clk_prepare_enable(data->clk);
+
+     return 0;
+}
+#endif
+
+static const struct dev_pm_ops mtk8250_pm_ops = {
+     SET_SYSTEM_SLEEP_PM_OPS(mtk8250_suspend, mtk8250_resume)
+     SET_RUNTIME_PM_OPS(mtk8250_runtime_suspend, mtk8250_runtime_resume,
+                             NULL)
+};
+
+static const struct of_device_id mtk8250_of_match[] = {
+     { .compatible = "mediatek,mt6577-uart" },
+     { /* Sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mtk8250_of_match);
+
+static struct platform_driver mtk8250_platform_driver = {
+     .driver = {
+             .name           = "mt6577-uart",
+             .owner          = THIS_MODULE,

This doesn't need to be set here,
module_platform_driver/platform_driver_register take care of setting it.

quoted

+             .pm             = &mtk8250_pm_ops,
+             .of_match_table = mtk8250_of_match,
+     },
+     .probe                  = mtk8250_probe,
+     .remove                 = mtk8250_remove,
+};
+module_platform_driver(mtk8250_platform_driver);
+
+MODULE_AUTHOR("Matthias Brugger");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Mediatek 8250 serial port driver");

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