linux-kernel - Re: [v6,10/23] drivers/fsi: Add device read/write/peek API

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Message-Id: <d2b26e2b-b488-886a-93c8-17db37e77b92@linux.vnet.ibm.com>
Date:   Tue, 2 May 2017 09:11:57 -0500
From:   Eddie James <eajames@...ux.vnet.ibm.com>
To:     Christopher Bostic <cbostic@...ux.vnet.ibm.com>
Cc:     robh+dt <robh+dt@...nel.org>,
        "mark.rutland" <mark.rutland@....com>, linux@...linux.org.uk,
        rostedt@...dmis.org, mingo@...hat.com, gregkh@...uxfoundation.org,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org, andrew <andrew@...id.au>,
        alistair@...ple.id.au, linux-kernel <linux-kernel@...r.kernel.org>,
        Jeremy Kerr <jk@...abs.org>, benh <benh@...nel.crashing.org>,
        joel <joel@....id.au>
Subject: Re: [v6,10/23] drivers/fsi: Add device read/write/peek API

On Apr 10, 2017, at 3:46 PM, Christopher Bostic 
<cbostic@...ux.vnet.ibm.com> wrote:
> From: Jeremy Kerr <jk@...abs.org>
>
> This change introduces the fsi device API: simple read, write and peek
> accessors for the devices' address spaces.
>
> Includes contributions from Chris Bostic <cbostic@...ux.vnet.ibm.com>
> and Edward A. James <eajames@...ibm.com>.
>
> Signed-off-by: Edward A. James <eajames@...ibm.com>
> Signed-off-by: Jeremy Kerr <jk@...abs.org>
> Signed-off-by: Chris Bostic <cbostic@...ux.vnet.ibm.com>
> Signed-off-by: Joel Stanley <joel@....id.au>
> ---
>  drivers/fsi/fsi-core.c | 33 +++++++++++++++++++++++++++++++++
>  include/linux/fsi.h    |  7 ++++++-
>  2 files changed, 39 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
> index a8faa89..4da0b030 100644
> --- a/drivers/fsi/fsi-core.c
> +++ b/drivers/fsi/fsi-core.c
> @@ -32,6 +32,8 @@
>  #define FSI_SLAVE_CONF_CRC_MASK        0x0000000f
>  #define FSI_SLAVE_CONF_DATA_BITS    28
>
> +#define FSI_PEEK_BASE            0x410
> +
>  static const int engine_page_size = 0x400;
>
>  #define FSI_SLAVE_BASE            0x800
> @@ -73,9 +75,40 @@ static int fsi_master_read(struct fsi_master 
> *master, int link,
>          uint8_t slave_id, uint32_t addr, void *val, size_t size);
>  static int fsi_master_write(struct fsi_master *master, int link,
>          uint8_t slave_id, uint32_t addr, const void *val, size_t size);
> +static int fsi_slave_read(struct fsi_slave *slave, uint32_t addr,
> +        void *val, size_t size);
> +static int fsi_slave_write(struct fsi_slave *slave, uint32_t addr,
> +        const void *val, size_t size);
>
>  /* FSI endpoint-device support */
>
> +int fsi_device_read(struct fsi_device *dev, uint32_t addr, void *val,
> +        size_t size)
> +{
> +    if (addr > dev->size || size > dev->size || addr > dev->size - size)
> +        return -EINVAL;
> +
> +    return fsi_slave_read(dev->slave, dev->addr + addr, val, size);
> +}
> +EXPORT_SYMBOL_GPL(fsi_device_read);
> +
> +int fsi_device_write(struct fsi_device *dev, uint32_t addr, const 
> void *val,
> +        size_t size)
> +{
> +    if (addr > dev->size || size > dev->size || addr > dev->size - size)
> +        return -EINVAL;
> +
> +    return fsi_slave_write(dev->slave, dev->addr + addr, val, size);
> +}
> +EXPORT_SYMBOL_GPL(fsi_device_write);
> +
> +int fsi_device_peek(struct fsi_device *dev, void *val)
> +{
> +    uint32_t addr = FSI_PEEK_BASE + ((dev->unit - 2) * 
> sizeof(uint32_t));
> +
> +    return fsi_slave_read(dev->slave, addr, val, sizeof(uint32_t));
> +}
> +
>  static void fsi_device_release(struct device *_device)
>  {
>      struct fsi_device *device = to_fsi_dev(_device);
> diff --git a/include/linux/fsi.h b/include/linux/fsi.h
> index efa55ba..66bce48 100644
> --- a/include/linux/fsi.h
> +++ b/include/linux/fsi.h
> @@ -27,6 +27,12 @@ struct fsi_device {
>      uint32_t        size;
>  };
>
> +extern int fsi_device_read(struct fsi_device *dev, uint32_t addr,
> +        void *val, size_t size);
> +extern int fsi_device_write(struct fsi_device *dev, uint32_t addr,
> +        const void *val, size_t size);
> +extern int fsi_device_peek(struct fsi_device *dev, void *val);
> +
>  struct fsi_device_id {
>      u8    engine_type;
>      u8    version;
> @@ -40,7 +46,6 @@ struct fsi_device_id {
>  #define FSI_DEVICE_VERSIONED(t, v) \
>      .engine_type = (t), .version = (v),
>
> -
>  struct fsi_driver {
>      struct device_driver        drv;
>      const struct fsi_device_id    *id_table;
>

I also wrote a driver against this API (an i2c algorithm). Everything 
looks good and working well.

Edward (Eddie) James <eajames@...ux.vnet.ibm.com>