Re: [PATCH 2/3] mtd: spi-nor: intel-spi: Convert to SPI MEM

[Mika Westerberg <mika.westerberg@linux.intel.com>]

Hi Andy,

On Mon, Oct 04, 2021 at 05:29:47PM +0300, Andy Shevchenko wrote:
> On Thu, Sep 30, 2021 at 1:08 PM Mika Westerberg
> <mika.westerberg@linux.intel.com> wrote:
> >
> > The preferred way to implement SPI-NOR controller drivers is through SPI
> > subsubsystem utilizing the SPI MEM core functions. This converts the
> > Intel SPI flash controller driver over the SPI MEM by moving the driver
> > from SPI-NOR subsystem to SPI subsystem and in one go make it use the
> > SPI MEM functions. The driver name will be changed from intel-spi to
> > spi-intel to match the convention used in the SPI subsystem.
> 
> ...
> 
> > +config SPI_INTEL_PCI
> > +       tristate "Intel PCH/PCU SPI flash PCI driver (DANGEROUS)"
> > +       depends on PCI && (X86 || COMPILE_TEST)
> 
> Perhaps two entries, one of which will be the same as for platform case?

Sure will do that in v2.

> > +       depends on SPI_MEM
> > +       select SPI_INTEL
> > +       help
> > +         This enables PCI support for the Intel PCH/PCU SPI controller in
> > +         master mode. This controller is present in modern Intel hardware
> > +         and is used to hold BIOS and other persistent settings. Using
> > +         this driver it is possible to upgrade BIOS directly from Linux.
> > +
> > +         Say N here unless you know what you are doing. Overwriting the
> > +         SPI flash may render the system unbootable.
> > +
> > +         To compile this driver as a module, choose M here: the module
> > +         will be called spi-intel-pci.
> > +
> > +config SPI_INTEL_PLATFORM
> > +       tristate "Intel PCH/PCU SPI flash platform driver (DANGEROUS)"
> > +       depends on X86 || COMPILE_TEST
> > +       depends on SPI_MEM
> > +       select SPI_INTEL
> > +       help
> > +         This enables platform support for the Intel PCH/PCU SPI
> > +         controller in master mode. This controller is present in modern
> > +         Intel hardware and is used to hold BIOS and other persistent
> > +         settings. Using this driver it is possible to upgrade BIOS
> > +         directly from Linux.
> > +
> > +         Say N here unless you know what you are doing. Overwriting the
> > +         SPI flash may render the system unbootable.
> > +
> > +         To compile this driver as a module, choose M here: the module
> > +         will be called spi-intel-platform.
> 
> ...
> 
> + Blank line ?

OK

> 
> >  #include <linux/mtd/partitions.h>
> >  #include <linux/mtd/spi-nor.h>
> 
> + Blank line?

OK

> > +#include <linux/spi/flash.h>
> > +#include <linux/spi/spi.h>
> > +#include <linux/spi/spi-mem.h>
> 
> The rationale is to show that we use two sub(sub)sytems here.

Yup, got it.

> ...
> 
> > -                       dev_err(ispi->dev, "read error: %llx: %#x\n", from,
> > +                       dev_err(ispi->dev, "read error: %x: %#x\n", from,
> >                                 status);
> 
> Now one line?
> 
> ...
> 
> > -                       dev_err(ispi->dev, "write error: %llx: %#x\n", to,
> > +                       dev_err(ispi->dev, "write error: %x: %#x\n", to,
> >                                 status);
> 
> Ditto.

Sure for both.
> 
> ...
> 
> > +               ret = intel_spi_sw_cycle(ispi, opcode, 0,
> > +                                        OPTYPE_WRITE_WITH_ADDR);
> > +               return ret ? ret : 0;
> 
> Why not simply return intel_spi_dw_cycle(...); ?

Good point. Will fix that.

> ...
> 
> > +       val = readl(ispi->base + HSFSTS_CTL);
> > +       val &= ~(HSFSTS_CTL_FDBC_MASK | HSFSTS_CTL_FCYCLE_MASK);
> > +       val |= HSFSTS_CTL_AEL | HSFSTS_CTL_FCERR | HSFSTS_CTL_FDONE;
> 
> > +       val |= cmd;
> > +       val |= HSFSTS_CTL_FGO;
> 
> Maybe swap these lines to group constants?

OK

> ...
> 
> > +       status = readl(ispi->base + HSFSTS_CTL);
> > +       if (status & HSFSTS_CTL_FCERR)
> > +               return -EIO;
> 
> > +       else if (status & HSFSTS_CTL_AEL)
> 
> Redundant 'else'

Right.

> > +               return -EACCES;
> 
> ...
> 
> > +static int intel_spi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
> > +{
> > +       struct intel_spi *ispi = spi_master_get_devdata(mem->spi->master);
> > +       size_t nbytes = op->data.nbytes;
> > +       u8 opcode = op->cmd.opcode;
> > +
> > +       if (op->addr.nbytes) {
> > +               if  (op->data.dir == SPI_MEM_DATA_IN)
> > +                       return intel_spi_read(ispi, op->addr.val, nbytes,
> > +                                             op->data.buf.in);
> 
> > +               else if (op->data.dir == SPI_MEM_DATA_OUT)
> 
> Redundant 'else' here and nearby.

Right. I'll fix these in v2.

> > +                       return intel_spi_write(ispi, op->addr.val, nbytes,
> > +                                              op->data.buf.out);
> > +               else if (op->data.dir == SPI_MEM_NO_DATA)
> > +                       return intel_spi_erase(ispi, opcode, op->addr.val);
> > +       } else {
> > +               if  (op->data.dir == SPI_MEM_DATA_IN)
> > +                       return intel_spi_read_reg(ispi, opcode, op->data.buf.in,
> > +                                                 nbytes);
> > +               else if (op->data.dir == SPI_MEM_DATA_OUT)
> > +                       return intel_spi_write_reg(ispi, opcode, op->data.buf.out,
> > +                                                  nbytes);
> > +               else if (op->data.dir == SPI_MEM_NO_DATA)
> > +                       return intel_spi_write_reg(ispi, opcode, NULL, 0);
> >         }
> 
> > +       return -EINVAL;
> > +}
> 
> -- 
> With Best Regards,
> Andy Shevchenko