linux-kernel - Re: [PATCH V7 2/4] MIPS: Add board support for Loongson1B

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Date:	Wed, 20 Jun 2012 20:25:51 +0100
From:	Ralf Baechle <ralf@...ux-mips.org>
To:	Kelvin Cheung <keguang.zhang@...il.com>
Cc:	linux-mips@...ux-mips.org, linux-kernel@...r.kernel.org,
	wuzhangjin@...il.com, zhzhl555@...il.com
Subject: Re: [PATCH V7 2/4] MIPS: Add board support for Loongson1B

On Fri, Jun 15, 2012 at 06:53:35PM +0800, Kelvin Cheung wrote:

> +#include <linux/clk.h>

> +static LIST_HEAD(clocks);
> +static DEFINE_MUTEX(clocks_mutex);
> +
> +struct clk *clk_get(struct device *dev, const char *name)
> +{
> +	struct clk *c;
> +	struct clk *ret = NULL;
> +
> +	mutex_lock(&clocks_mutex);
> +	list_for_each_entry(c, &clocks, node) {
> +		if (!strcmp(c->name, name)) {
> +			ret = c;
> +			break;
> +		}
> +	}
> +	mutex_unlock(&clocks_mutex);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(clk_get);

This redefines a function that already is declared in <linux/clk.h> and
defined in drivers/clk/clkdev.c.  Why?

> +int clk_register(struct clk *clk)
> +{
> +	mutex_lock(&clocks_mutex);
> +	list_add(&clk->node, &clocks);
> +	if (clk->ops->init)
> +		clk->ops->init(clk);
> +	mutex_unlock(&clocks_mutex);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(clk_register);

Same here.

> diff --git a/arch/mips/loongson1/common/prom.c b/arch/mips/loongson1/common/prom.c
> new file mode 100644
> index 0000000..1f8e49f
> --- /dev/null
> +++ b/arch/mips/loongson1/common/prom.c
> @@ -0,0 +1,87 @@
> +/*
> + * Copyright (c) 2011 Zhang, Keguang <keguang.zhang@...il.com>
> + *
> + * Modified from arch/mips/pnx833x/common/prom.c.
> + *
> + * This program is free software; you can redistribute  it and/or modify it
> + * under  the terms of  the GNU General  Public License as published by the
> + * Free Software Foundation;  either version 2 of the  License, or (at your
> + * option) any later version.
> + */
> +
> +#include <linux/serial_reg.h>
> +#include <asm/bootinfo.h>
> +
> +#include <loongson1.h>
> +#include <prom.h>
> +
> +int prom_argc;
> +char **prom_argv, **prom_envp;
> +unsigned long memsize, highmemsize;
> +
> +char *prom_getenv(char *envname)
> +{
> +	char **env = prom_envp;
> +	int i;
> +
> +	i = strlen(envname);
> +
> +	while (*env) {
> +		if (strncmp(envname, *env, i) == 0 && *(*env+i) == '=')
> +			return *env + i + 1;
> +		env++;
> +	}
> +
> +	return 0;
> +}
[...]

Please take a look at sjhill's firmware cleanup patchset which is going to
remove a fair chunk of duplication of firmware related code.

This is just a heads up; you need to do nothing because that patchset is not
applied yet.)

> +const char *get_system_type(void)
> +{
> +	unsigned int processor_id = (&current_cpu_data)->processor_id;
> +
> +	switch (processor_id & PRID_REV_MASK) {
> +	case PRID_REV_LOONGSON1B:
> +		return "LOONGSON LS1B";
> +	default:
> +		return "LOONGSON (unknown)";
> +	}
> +}

You probably should return a string identifying the system, not the SOC
being used.  So this function should probably go to board.c.

> diff --git a/arch/mips/loongson1/ls1b/board.c b/arch/mips/loongson1/ls1b/board.c
> new file mode 100644
> index 0000000..1ec350d
> --- /dev/null
> +++ b/arch/mips/loongson1/ls1b/board.c
> @@ -0,0 +1,39 @@
> +/*
> + * Copyright (c) 2011 Zhang, Keguang <keguang.zhang@...il.com>
> + *
> + * This program is free software; you can redistribute  it and/or modify it
> + * under  the terms of  the GNU General  Public License as published by the
> + * Free Software Foundation;  either version 2 of the  License, or (at your
> + * option) any later version.
> + */
> +
> +#include <platform.h>
> +
> +#include <linux/serial_8250.h>
> +#include <loongson1.h>
> +
> +static struct platform_device *ls1b_platform_devices[] __initdata = {
> +	&ls1x_uart_device,
> +#if IS_ENABLED(CONFIG_STMMAC_ETH)
> +	&ls1x_eth0_device,
> +#endif
> +#if IS_ENABLED(CONFIG_USB_EHCI_HCD)
> +	&ls1x_ehci_device,
> +#endif
> +#if IS_ENABLED(CONFIG_RTC_DRV_LOONGSON1)
> +	&ls1x_rtc_device,
> +#endif
> +};

Don't ifdef the platform devices.  The platform devices should always
be registered if a system actually has the underlying hardware.  If the
driver has been compiled or not does not matter.

And the final plug - take a look at FDT for a future revision of this
code :)

  Ralf
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