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SubjectRe: [PATCH v3 4/4] ARM: msm: Describe MSM 8660 SURF FPGA registers in DT
Date
On Thursday 18 August 2011, David Brown wrote:
> +static void __init msm8660_surf_fpga_init(void __iomem *fpga_mem)
> +{
> + /* Advanced mode */
> + writew(0xFFFF, fpga_mem + 0x15C);
> + /* FPGA_UART_SEL */
> + writew(0, fpga_mem + 0x172);
> + /* FPGA_GPIO_CONFIG_117 */
> + writew(1, fpga_mem + 0xEA);
> + /* FPGA_GPIO_CONFIG_118 */
> + writew(1, fpga_mem + 0xEC);
> + dmb();
> +}

Does the dmb() do the right thing here? It seems strange to combine a strictly
ordered I/O instruction with another ordering instruction, and I think it would
be better to use writew_relaxed for the first one, followed by a 'wmb()'.

> +#ifdef CONFIG_OF
> +static void __init msm8660_surf_fpga_init_dt(void)
> +{
> + struct device_node *node;
> + void __iomem *fpga_mem;
> +
> + node = of_find_compatible_node(NULL, NULL, "qcom,msm8660-surf-fpga");
> + if (!node)
> + return;
> +
> + fpga_mem = of_iomap(node, 0);
> + of_node_put(node);
> + if (!fpga_mem) {
> + printk(KERN_ERR "%s: Can't map fpga registers\n", __func__);
> + return;
> + }
> +
> + msm8660_surf_fpga_init(fpga_mem);
> + iounmap(fpga_mem);
> +}
> +#endif

Is the serial port connected through the FPGA or just configured by it?

In the former case, I think it would be better to make this a proper device driver that
binds to the qcom,msm8660-surf-fpga device, configures it and then creates the
platform_devices for the child nodes (the serial port, possibly others) by calling
of_platform_bus_probe.

Arnd


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