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Message-ID: <1426029133.17565.9.camel@kernel.crashing.org>
Date: Wed, 11 Mar 2015 10:12:13 +1100
From: Benjamin Herrenschmidt <benh@...nel.crashing.org>
To: Neelesh Gupta <neelegup@...ux.vnet.ibm.com>
Cc: Wolfram Sang <wsa@...-dreams.de>, linux-i2c@...r.kernel.org,
linux-mips@...ux-mips.org, linux-kernel@...r.kernel.org,
Ludovic Desroches <ludovic.desroches@...el.com>,
Yingjoe Chen <yingjoe.chen@...iatek.com>,
Eddie Huang <eddie.huang@...iatek.com>,
linuxppc-dev@...ts.ozlabs.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC V2 04/12] i2c: opal: make use of the new infrastructure
for quirks
On Tue, 2015-03-10 at 22:43 +0530, Neelesh Gupta wrote:
> I tested the i2c opal driver after updating the patch as below.
> Basically I think we can also support write-then-{read/write}
> for the number of messages = 2.
> Ben, any issues if we support both write plus read/write in the
> opal driver ?
Nope, in fact it's a good idea, I found myself having to expoes such
an interface to some userspace tool of ours.
However...
> diff --git a/drivers/i2c/busses/i2c-opal.c b/drivers/i2c/busses/i2c-opal.c
> index 16f90b1..85412ba 100644
> --- a/drivers/i2c/busses/i2c-opal.c
> +++ b/drivers/i2c/busses/i2c-opal.c
> @@ -104,18 +104,8 @@ static int i2c_opal_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> req.buffer_ra = cpu_to_be64(__pa(msgs[0].buf));
> break;
> case 2:
> - /* For two messages, we basically support only simple
> - * smbus transactions of a write plus a read. We might
> - * want to allow also two writes but we'd have to bounce
> - * the data into a single buffer.
> - */
> - if ((msgs[0].flags & I2C_M_RD) || !(msgs[1].flags & I2C_M_RD))
> - return -EOPNOTSUPP;
Don't we still want to enforce that the first message is a write ?
Somebody may not be looking at the quirks...
> - if (msgs[0].len > 4)
> - return -EOPNOTSUPP;
And that the len is supported...
> - if (msgs[0].addr != msgs[1].addr)
> - return -EOPNOTSUPP;
Same...
Ie, the quirk indicates to the callers what we support, but we should
still check that we aren't called with something that doesn't match.
> - req.type = OPAL_I2C_SM_READ;
> + req.type = (msgs[1].flags & I2C_M_RD) ?
> + OPAL_I2C_SM_READ : OPAL_I2C_SM_WRITE;
> req.addr = cpu_to_be16(msgs[0].addr);
> req.subaddr_sz = msgs[0].len;
> for (i = 0; i < msgs[0].len; i++)
> @@ -210,6 +200,11 @@ static const struct i2c_algorithm i2c_opal_algo = {
> .functionality = i2c_opal_func,
> };
>
> +static struct i2c_adapter_quirks i2c_opal_quirks = {
> + .flags = I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST | I2C_AQ_COMB_SAME_ADDR,
> + .max_comb_1st_msg_len = 4,
> +};
> +
> static int i2c_opal_probe(struct platform_device *pdev)
> {
> struct i2c_adapter *adapter;
> @@ -232,6 +227,7 @@ static int i2c_opal_probe(struct platform_device *pdev)
>
> adapter->algo = &i2c_opal_algo;
> adapter->algo_data = (void *)(unsigned long)opal_id;
> + adapter->quirks = &i2c_opal_quirks;
> adapter->dev.parent = &pdev->dev;
> adapter->dev.of_node = of_node_get(pdev->dev.of_node);
> pname = of_get_property(pdev->dev.of_node, "ibm,port-name", NULL);
>
>
>
> On 02/25/2015 09:31 PM, Wolfram Sang wrote:
> > From: Wolfram Sang <wsa+renesas@...g-engineering.com>
> >
> > Signed-off-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
> > ---
> > drivers/i2c/busses/i2c-opal.c | 22 +++++++++++-----------
> > 1 file changed, 11 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-opal.c b/drivers/i2c/busses/i2c-opal.c
> > index 16f90b1a750894..b2788ecad5b3cb 100644
> > --- a/drivers/i2c/busses/i2c-opal.c
> > +++ b/drivers/i2c/busses/i2c-opal.c
> > @@ -104,17 +104,6 @@ static int i2c_opal_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> > req.buffer_ra = cpu_to_be64(__pa(msgs[0].buf));
> > break;
> > case 2:
> > - /* For two messages, we basically support only simple
> > - * smbus transactions of a write plus a read. We might
> > - * want to allow also two writes but we'd have to bounce
> > - * the data into a single buffer.
> > - */
> > - if ((msgs[0].flags & I2C_M_RD) || !(msgs[1].flags & I2C_M_RD))
> > - return -EOPNOTSUPP;
> > - if (msgs[0].len > 4)
> > - return -EOPNOTSUPP;
> > - if (msgs[0].addr != msgs[1].addr)
> > - return -EOPNOTSUPP;
> > req.type = OPAL_I2C_SM_READ;
> > req.addr = cpu_to_be16(msgs[0].addr);
> > req.subaddr_sz = msgs[0].len;
> > @@ -210,6 +199,16 @@ static const struct i2c_algorithm i2c_opal_algo = {
> > .functionality = i2c_opal_func,
> > };
> >
> > +/* For two messages, we basically support only simple
> > + * smbus transactions of a write plus a read. We might
> > + * want to allow also two writes but we'd have to bounce
> > + * the data into a single buffer.
> > + */
> > +static struct i2c_adapter_quirks i2c_opal_quirks = {
> > + .flags = I2C_AQ_COMB_WRITE_THEN_READ,
> > + .max_comb_1st_msg_len = 4,
> > +};
> > +
> > static int i2c_opal_probe(struct platform_device *pdev)
> > {
> > struct i2c_adapter *adapter;
> > @@ -232,6 +231,7 @@ static int i2c_opal_probe(struct platform_device *pdev)
> >
> > adapter->algo = &i2c_opal_algo;
> > adapter->algo_data = (void *)(unsigned long)opal_id;
> > + adapter->quirks = &i2c_opal_quirks;
> > adapter->dev.parent = &pdev->dev;
> > adapter->dev.of_node = of_node_get(pdev->dev.of_node);
> > pname = of_get_property(pdev->dev.of_node, "ibm,port-name", NULL);
--
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