linux-kernel - Re: [PATCH 3/8] regmap: Add support for using regmap over ssbi

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Date:	Tue, 10 Dec 2013 17:32:51 -0800
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Mark Brown <broonie@...nel.org>
CC:	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	Srinivas Ramana <sramana@...eaurora.org>,
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 3/8] regmap: Add support for using regmap over ssbi

On 12/10/13 16:51, Mark Brown wrote:
> On Tue, Dec 10, 2013 at 04:13:15PM -0800, Stephen Boyd wrote:
>> increment reg by 1 every time through this loop. Or should we just have
>> use_single_rw == true?
> No, it doesn't - it increments the address of reg by the size of a
> register value each time.  Using use_single_rw might make sense, or if
> you can't do bulk I/O at all then hooking in via reg_read() and
> reg_write() in the config rather than trying to parse out the buffers
> might be even better (you can still make helpers to set that up).


Are you suggesting we implement the reg_read/reg_write as global helpers
that the config points to and then call regmap_init()? At a quick glance
it looks like we lose out on regmap_bulk_read() if we do that. There is
one driver that will use regmap_bulk_read(), but I suppose we can just
loop on regmap_read() and do our own increment? If we use use_single_rw
everything works and we can simplify this code to just pass the reg and
val buffers directly to ssbi_read/write.

This is what I have now.

static int regmap_ssbi_read(void *context,
                            const void *regp, size_t reg_size,
                            void *val, size_t val_size)
{
        int ret;
        u16 reg;

        BUG_ON(reg_size != 2);

        reg = *(u16 *)regp;
        while (val_size) {
                ret = ssbi_read(context, reg, val, 1);
                if (ret)
                        return ret;
                reg++;
                val += sizeof(u8);
                val_size -= sizeof(u8);
        }

        return 0;
}

With use_single_rw I think it can be this.

static int regmap_ssbi_read(void *context,
                            const void *reg, size_t reg_size,
                            void *val, size_t val_size)
{
        BUG_ON(reg_size != 2);  
        return ssbi_read(context, *(u16 *)reg, val, 1);
}

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