Re: [PATCH 5/7] Add MCI card support to barebox

[Sascha Hauer <s.hauer@pengutronix.de>]

On Thu, Oct 07, 2010 at 06:00:06PM +0200, Juergen Beisert wrote:
> Sascha Hauer wrote:
> > On Thu, Oct 07, 2010 at 03:24:16PM +0200, Juergen Beisert wrote:
> > > This adds the basic framework to handle MCI cards in barebox.
> > >
> > > Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
> > > ---
> > >  drivers/Kconfig        |    1 +
> > >  drivers/Makefile       |    1 +
> > >  drivers/mci/Kconfig    |   30 ++
> > >  drivers/mci/Makefile   |    1 +
> > >  drivers/mci/mci-core.c | 1308
> > > ++++++++++++++++++++++++++++++++++++++++++++++++ include/mci.h          |
> > >  230 +++++++++
> > >  6 files changed, 1571 insertions(+), 0 deletions(-)
> > >  create mode 100644 drivers/mci/Kconfig
> > >  create mode 100644 drivers/mci/Makefile
> > >  create mode 100644 drivers/mci/mci-core.c
> > >  create mode 100644 include/mci.h
> >
> > This whole patch looks quite good.
> > Please add some linebreaks in mci-core.c. I don't want strict 80
> > character lines, but some lines are really long.
> >
> > [snip]
> >
> > > +static int mci_probe(struct device_d *mci_dev)
> > > +{
> > > +	struct mci *mci;
> > > +	int rc;
> > > +
> > > +	mci = xzalloc(sizeof(struct mci));
> > > +	mci_dev->priv = mci;
> > > +
> > > +#ifdef CONFIG_MCI_STARTUP
> > > +	/* if enabled, probe the attached card immediately */
> > > +	rc = mci_card_probe(mci_dev);
> > > +	if (rc == -ENODEV) {
> > > +		/*
> > > +		 * If it fails, add the 'probe' parameter to give the user
> > > +		 * a chance to insert a card and try again. Note: This may fail
> > > +		 * systems that rely on the MCI card for startup (for the
> > > +		 * persistant environment for example)
> > > +		 */
> > > +		rc = add_mci_parameter(mci_dev);
> > > +		if (rc != 0) {
> > > +			pr_err("Failed to add 'probe' parameter to the MCI device\n");
> > > +			goto on_error;
> > > +		}
> > > +	}
> > > +#endif
> > > +
> > > +#ifndef CONFIG_MCI_STARTUP
> >
> > #else instead?
> >
> > > +	/* add params on demand */
> > > +	rc = add_mci_parameter(mci_dev);
> > > +	if (rc != 0) {
> > > +		pr_err("Failed to add 'probe' parameter to the MCI device\n");
> > > +		goto on_error;
> > > +	}
> > > +#endif
> > > +
> > > +	return rc;
> > > +
> > > +on_error:
> > > +	free(mci);
> > > +	return rc;
> > > +}
> > > +
> >
> > [snip]
> >
> > > +
> > > +/** host information */
> > > +struct mci_platformdata {
> > > +	struct device_d *hw_dev;	/**< the host MCI hardware device */
> > > +	unsigned voltages;
> > > +	unsigned host_caps;	/**< Host's interface capabilities, refer MMC_VDD_*
> > > and FIXME */ +	unsigned f_min;		/**< host interface lower limit */
> > > +	unsigned f_max;		/**< host interface upper limit */
> > > +	unsigned clock;		/**< Current clock used to talk to the card */
> > > +	unsigned bus_width;	/**< used data bus width to the card */
> > > +
> > > +	int (*init)(struct device_d*, struct device_d*);	/**< init the host
> > > interface */ +	void (*set_ios)(struct device_d*, struct device_d*,
> > > unsigned, unsigned);	/**< change host interface settings */ +	int
> > > (*send_cmd)(struct device_d*, struct mci_cmd*, struct mci_data*);	/**<
> > > handle a command */ +};
> >
> > I prefer this struct named mci_host, this seems to match better what it
> > actually is.
> 
> Hmm, no, its not a "host". It is the MMC/SD card instance. The host is more 
> the interface, isn't it (at least for me)?

It's a host at least in the Linux terminology.

> 
> > For the convenience of drivers set init/set_ios/send_cmd 
> > functions should be passed a pointer to the mci_host, not the device,
> > because that's what they actually registered. I already prepared a patch
> > for this, I'll send it in a seperate mail.
> 
> I tried to layering the devices:
> 
>  disk_device -> knows how to handle disk drives and partition tables
>     |
>  mci_device -> knows how to probe and manage MMC/SD cards
>     |
>  hw_device -> knows how to transfer data
> 
> Most functions in the hw_device layer do not need access to any other 
> structure data than their own device (okay, there is a exception). So, I 
> tried to keep it simple.

I didn't change the underlying structure, only the pointer which is
passed to the functions.

Sascha


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