Re: [PATCH v2 1/2] net: dsa: ksz9477: add I2C managed mode support

[Sergio Paracuellos <sergio.paracuellos@gmail.com>]

On Mon, Dec 17, 2018 at 8:38 AM Andrew Lunn <andrew@lunn.ch> wrote:
>
> On Sun, Dec 16, 2018 at 10:49:52AM +0100, Sergio Paracuellos wrote:
> > In this mode the switch device and the internal phys will be managed via
> > I2C interface.
> >
> > Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
> > ---
> > Changes v2:
> >     - Use dev->txbuf as transmition buffer which is allocated using
> >       kernel allocators avoiding some possible DMA issues using the
> >       stack.
> >  drivers/net/dsa/microchip/Kconfig       |   6 +
> >  drivers/net/dsa/microchip/Makefile      |   1 +
> >  drivers/net/dsa/microchip/ksz9477_i2c.c | 269 ++++++++++++++++++++++++
> >  3 files changed, 276 insertions(+)
> >  create mode 100644 drivers/net/dsa/microchip/ksz9477_i2c.c
> >
> > diff --git a/drivers/net/dsa/microchip/Kconfig b/drivers/net/dsa/microchip/Kconfig
> > index a8caf9249d50..162fec43d204 100644
> > --- a/drivers/net/dsa/microchip/Kconfig
> > +++ b/drivers/net/dsa/microchip/Kconfig
> > @@ -14,3 +14,9 @@ config NET_DSA_MICROCHIP_KSZ9477_SPI
> >       depends on NET_DSA_MICROCHIP_KSZ9477 && SPI
> >       help
> >         Select to enable support for registering switches configured through SPI.
> > +
> > +config NET_DSA_MICROCHIP_KSZ9477_I2C
> > +     tristate "KSZ series I2C connected switch driver"
> > +     depends on NET_DSA_MICROCHIP_KSZ9477 && I2C
> > +     help
> > +       Select to enable support for registering switches configured through I2C.
> > diff --git a/drivers/net/dsa/microchip/Makefile b/drivers/net/dsa/microchip/Makefile
> > index 3142c18b8f57..eb9b768face2 100644
> > --- a/drivers/net/dsa/microchip/Makefile
> > +++ b/drivers/net/dsa/microchip/Makefile
> > @@ -1,3 +1,4 @@
> >  obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ_COMMON)   += ksz_common.o
> >  obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ9477)              += ksz9477.o
> >  obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ9477_SPI)  += ksz9477_spi.o
> > +obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ9477_I2C)  += ksz9477_i2c.o
> > diff --git a/drivers/net/dsa/microchip/ksz9477_i2c.c b/drivers/net/dsa/microchip/ksz9477_i2c.c
> > new file mode 100644
> > index 000000000000..3c9cba6e254b
> > --- /dev/null
> > +++ b/drivers/net/dsa/microchip/ksz9477_i2c.c
> > @@ -0,0 +1,269 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Microchip KSZ series register access through I2C
> > + *
> > + * Author: Sergio Paracuellos <sergio.paracuellos@gmail.com>
> > + */
> > +
> > +#include <linux/i2c.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +
> > +#include "ksz_priv.h"
> > +
> > +/* Enough to read all switch port registers. */
> > +#define I2C_TX_BUF_LEN                  0x100
> > +
> > +/**
> > + * ksz_i2c_read_reg - issue read register command
> > + * @client: i2c client structure
> > + * @reg: The register address.
> > + * @val: The buffer to return the result into.
> > + * @len: The length of data expected.
> > + *
> > + * This is the low level read call that issues the necessary i2c message(s)
> > + * to read data from the register specified in @reg.
> > + */
> > +static int ksz_i2c_read_reg(struct i2c_client *client, u32 reg, u8 *val,
> > +                         unsigned int len)
> > +{
> > +     struct i2c_adapter *adapter = client->adapter;
> > +     struct i2c_msg msg[2];
> > +     int ret;
> > +
> > +     msg[0].addr = client->addr;
> > +     msg[0].flags = 0;
> > +     msg[0].len = 2;
> > +     msg[0].buf = val;
> > +
> > +     msg[1].addr = client->addr;
> > +     msg[1].flags = I2C_M_RD;
> > +     msg[1].len = len;
> > +     msg[1].buf = val;
> > +
> > +     ret = i2c_transfer(adapter, msg, 2);
> > +     return (ret != 2) ? -EREMOTEIO : 0;
> > +}
> > +
> > +static int ksz_i2c_read(struct ksz_device *dev, u32 reg, u8 *data,
> > +                     unsigned int len)
> > +{
> > +     struct i2c_client *client = dev->priv;
> > +     int ret;
> > +
> > +     len = (len > I2C_TX_BUF_LEN) ? I2C_TX_BUF_LEN : len;
> > +     dev->txbuf[0] = (u8)(reg >> 8);
> > +     dev->txbuf[1] = (u8)reg;
> > +
> > +     ret = ksz_i2c_read_reg(client, reg, dev->txbuf, len);
> > +     if (!ret)
> > +             memcpy(data, dev->txbuf, len);
> > +
> > +     return ret;
> > +}
> > +
> > +static int ksz_i2c_read8(struct ksz_device *dev, u32 reg, u8 *val)
> > +{
> > +     return ksz_i2c_read(dev, reg, val, 1);
> > +}
> > +
> > +static int ksz_i2c_read16(struct ksz_device *dev, u32 reg, u16 *val)
> > +{
> > +     int ret = ksz_i2c_read(dev, reg, (u8 *)val, 2);
> > +
> > +     if (!ret)
> > +             *val = be16_to_cpu(*val);
> > +
> > +     return ret;
> > +}
> > +
> > +static int ksz_i2c_read24(struct ksz_device *dev, u32 reg, u32 *val)
> > +{
> > +     int ret;
> > +
> > +     *val = 0;
> > +     ret = ksz_i2c_read(dev, reg, (u8 *)val, 3);
> > +
> > +     if (!ret) {
> > +             *val = be32_to_cpu(*val);
> > +             /* convert to 24 bit */
> > +             *val >>= 8;
> > +     }
> > +
> > +     return ret;
> > +}
> > +
> > +static int ksz_i2c_read32(struct ksz_device *dev, u32 reg, u32 *val)
> > +{
> > +     int ret = ksz_i2c_read(dev, reg, (u8 *)val, 4);
> > +
> > +     if (!ret)
> > +             *val = be32_to_cpu(*val);
> > +
> > +     return ret;
> > +}
> > +
> > +/**
> > + * ksz_i2c_write_reg - issue write register command
> > + * @client: i2c client structure
> > + * @reg: The register address.
> > + * @val: value to write
> > + * @len: The length of data
> > + *
> > + * This is the low level write call that issues the necessary i2c message(s)
> > + * to write data to the register specified in @reg.
> > + */
> > +static int ksz_i2c_write_reg(struct i2c_client *client, u32 reg, u8 *val,
> > +                          unsigned int len)
> > +{
> > +     struct i2c_adapter *adapter = client->adapter;
> > +     struct i2c_msg msg;
> > +     int ret;
> > +
> > +     msg.addr = client->addr;
> > +     msg.flags = 0;
> > +     msg.len = 2 + len;
> > +     msg.buf = val;
> > +
> > +     ret = i2c_transfer(adapter, &msg, 1);
> > +     return (ret != 1) ? -EREMOTEIO : 0;
> > +}
> > +
> > +static int ksz_i2c_write(struct ksz_device *dev, u32 reg, u8 *val,
> > +                      unsigned int len)
> > +{
> > +     struct i2c_client *client = dev->priv;
> > +     unsigned int cnt = len;
> > +     int i;
> > +
> > +     len = (len > I2C_TX_BUF_LEN) ? I2C_TX_BUF_LEN : len;
> > +     dev->txbuf[0] = (u8)(reg >> 8);
> > +     dev->txbuf[1] = (u8)reg;
> > +     i = 2;
> > +
> > +     do {
> > +             dev->txbuf[i++] = (u8)(*val >> (8 * (cnt - 1)));
> > +             cnt--;
> > +     } while (cnt);
> > +
> > +     return ksz_i2c_write_reg(client, reg, dev->txbuf, len);
> > +}
> > +
> > +static int ksz_i2c_write8(struct ksz_device *dev, u32 reg, u8 value)
> > +{
> > +     return ksz_i2c_write(dev, reg, &value, 1);
> > +}
> > +
> > +static int ksz_i2c_write16(struct ksz_device *dev, u32 reg, u16 value)
> > +{
> > +     value = cpu_to_be16(value);
> > +     return ksz_i2c_write(dev, reg, (u8 *)&value, 2);
> > +}
> > +
> > +static int ksz_i2c_write24(struct ksz_device *dev, u32 reg, u32 value)
> > +{
> > +     /* make it to big endian 24bit from MSB */
> > +     value <<= 8;
> > +     value = cpu_to_be32(value);
> > +
> > +     return ksz_i2c_write(dev, reg, (u8 *)&value, 3);
> > +}
> > +
> > +static int ksz_i2c_write32(struct ksz_device *dev, u32 reg, u32 value)
> > +{
> > +     value = cpu_to_be32(value);
> > +     return ksz_i2c_write(dev, reg, (u8 *)&value, 4);
> > +}
> > +
> > +static int ksz_i2c_get(struct ksz_device *dev, u32 reg, void *data, size_t len)
> > +{
> > +     return ksz_i2c_read(dev, reg, data, len);
> > +}
> > +
> > +static int ksz_i2c_set(struct ksz_device *dev, u32 reg, void *data, size_t len)
> > +{
> > +     return ksz_i2c_write(dev, reg, data, len);
> > +}
> > +
> > +static const struct ksz_io_ops ksz_i2c_ops = {
> > +     .read8 = ksz_i2c_read8,
> > +     .read16 = ksz_i2c_read16,
> > +     .read24 = ksz_i2c_read24,
> > +     .read32 = ksz_i2c_read32,
> > +     .write8 = ksz_i2c_write8,
> > +     .write16 = ksz_i2c_write16,
> > +     .write24 = ksz_i2c_write24,
> > +     .write32 = ksz_i2c_write32,
> > +     .get = ksz_i2c_get,
> > +     .set = ksz_i2c_set,
> > +};
> > +
> > +static int ksz_i2c_probe(struct i2c_client *client,
> > +                      const struct i2c_device_id *id)
> > +{
> > +     struct ksz_device *dev;
> > +     int ret;
> > +
> > +     dev = ksz_switch_alloc(&client->dev, &ksz_i2c_ops, client);
> > +     if (!dev)
> > +             return -ENOMEM;
> > +
> > +     if (client->dev.platform_data)
> > +             dev->pdata = client->dev.platform_data;
> > +
> > +     dev->txbuf = devm_kzalloc(dev->dev, 2 + I2C_TX_BUF_LEN, GFP_KERNEL);
> > +     if (!dev->txbuf)
> > +             return -ENOMEM;
> > +
> > +     i2c_set_clientdata(client, dev);
> > +
> > +     ret = ksz9477_switch_register(dev);
> > +     if (ret) {
> > +             dev_err(&client->dev, "registering switch (ret: %d)\n", ret);
> > +             return ret;
> > +     }
>
> Dan's comments appear to apply to this version as well.

Yes, Andrew. I sent v2 yesterday before Dan's comments. Please see my
answers in that mail thread.
>
>       Andrew

Best regards,
    Sergio Paracuellos