linux-kernel - Re: [PATCH v3 6/6] clk: axi-clkgen: Add support for FPGA info

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Message-ID: <CA+U=Dsqujj=Mf6ES0zt+atEO835eRB+xV29X_68Ah1hTo-pysw@mail.gmail.com>
Date:   Thu, 24 Sep 2020 17:53:59 +0300
From:   Alexandru Ardelean <ardeleanalex@...il.com>
To:     Moritz Fischer <mdf@...nel.org>
Cc:     Alexandru Ardelean <alexandru.ardelean@...log.com>,
        linux-clk@...r.kernel.org, linux-fpga@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Mircea Caprioru <mircea.caprioru@...log.com>
Subject: Re: [PATCH v3 6/6] clk: axi-clkgen: Add support for FPGA info

On Thu, Sep 24, 2020 at 5:21 PM Moritz Fischer <mdf@...nel.org> wrote:
>
> On Thu, Sep 24, 2020 at 09:50:12AM +0300, Alexandru Ardelean wrote:
> > From: Mircea Caprioru <mircea.caprioru@...log.com>
> >
> > This patch adds support for vco maximum and minimum ranges in accordance
> > with fpga speed grade, voltage, device package, technology and family. This
> > new information is extracted from two new registers implemented in the ip
> > core: ADI_REG_FPGA_INFO and ADI_REG_FPGA_VOLTAGE, which are stored in the
> > 'include/linux/fpga/adi-axi-common.h' file as they are common to all ADI
> > FPGA cores.
> >
> > Signed-off-by: Mircea Caprioru <mircea.caprioru@...log.com>
> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
> > ---
> >  drivers/clk/clk-axi-clkgen.c | 67 +++++++++++++++++++++++++++++++-----
> >  1 file changed, 59 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/clk/clk-axi-clkgen.c b/drivers/clk/clk-axi-clkgen.c
> > index 6ffc19e9d850..b03ea28270cb 100644
> > --- a/drivers/clk/clk-axi-clkgen.c
> > +++ b/drivers/clk/clk-axi-clkgen.c
> > @@ -8,6 +8,7 @@
> >
> >  #include <linux/platform_device.h>
> >  #include <linux/clk-provider.h>
> > +#include <linux/fpga/adi-axi-common.h>
> >  #include <linux/slab.h>
> >  #include <linux/io.h>
> >  #include <linux/of.h>
> > @@ -49,6 +50,7 @@
> >  struct axi_clkgen {
> >       void __iomem *base;
> >       struct clk_hw clk_hw;
> > +     unsigned int pcore_version;
> >  };
> >
> >  static uint32_t axi_clkgen_lookup_filter(unsigned int m)
> > @@ -101,15 +103,15 @@ static uint32_t axi_clkgen_lookup_lock(unsigned int m)
> >  }
> >
> >  #ifdef ARCH_ZYNQMP
> > -static const unsigned int fpfd_min = 10000;
> > -static const unsigned int fpfd_max = 450000;
> > -static const unsigned int fvco_min = 800000;
> > -static const unsigned int fvco_max = 1600000;
> > +static unsigned int fpfd_min = 10000;
> > +static unsigned int fpfd_max = 450000;
> > +static unsigned int fvco_min = 800000;
> > +static unsigned int fvco_max = 1600000;
> >  #else
> > -static const unsigned int fpfd_min = 10000;
> > -static const unsigned int fpfd_max = 300000;
> > -static const unsigned int fvco_min = 600000;
> > -static const unsigned int fvco_max = 1200000;
> > +static unsigned int fpfd_min = 10000;
> > +static unsigned int fpfd_max = 300000;
> > +static unsigned int fvco_min = 600000;
> > +static unsigned int fvco_max = 1200000;
> >  #endif
> Instead of modifying those wouldn't you want those to be part of your
> struct axi_clkgen? I understand that they're technically properties of the
> fabric you're implementing this IP block in, but are you sure you'll
> never have a system with more than one of those in two different FPGAs,
> are you never gonna use this beyond ARCH_ZYNQ/ZYNQMP/MICROBLAZE?
>
> What about a PCIe plugin card for a ZynqMP system with a Zynq on it?

That is a good point.
Will think about this, and re-implement it per axi_clkgen.
These FPGA can be combined in complex [sometimes weird] ways.

> >
> >  static void axi_clkgen_calc_params(unsigned long fin, unsigned long fout,
> > @@ -229,6 +231,49 @@ static void axi_clkgen_read(struct axi_clkgen *axi_clkgen,
> >       *val = readl(axi_clkgen->base + reg);
> >  }
> >
> > +static void axi_clkgen_setup_ranges(struct axi_clkgen *axi_clkgen)
> > +{
> > +     unsigned int reg_value;
> > +     unsigned int tech, family, speed_grade, voltage;
> > +
> > +     axi_clkgen_read(axi_clkgen, ADI_AXI_REG_FPGA_INFO, &reg_value);
> > +     tech = ADI_AXI_INFO_FPGA_TECH(reg_value);
> > +     family = ADI_AXI_INFO_FPGA_FAMILY(reg_value);
> > +     speed_grade = ADI_AXI_INFO_FPGA_SPEED_GRADE(reg_value);
> > +
> > +     axi_clkgen_read(axi_clkgen, ADI_AXI_REG_FPGA_VOLTAGE, &reg_value);
> > +     voltage = ADI_AXI_INFO_FPGA_VOLTAGE(reg_value);
> > +
> > +     switch (speed_grade) {
> > +     case ADI_AXI_FPGA_SPEED_GRADE_XILINX_1 ... ADI_AXI_FPGA_SPEED_GRADE_XILINX_1LV:
> > +             fvco_max = 1200000;
> > +             fpfd_max = 450000;
> > +             break;
> > +     case ADI_AXI_FPGA_SPEED_GRADE_XILINX_2 ... ADI_AXI_FPGA_SPEED_GRADE_XILINX_2LV:
> > +             fvco_max = 1440000;
> > +             fpfd_max = 500000;
> > +             if ((family == ADI_AXI_FPGA_FAMILY_XILINX_KINTEX) |
> > +                 (family == ADI_AXI_FPGA_FAMILY_XILINX_ARTIX)) {
> > +                     if (voltage < 950) {
> > +                             fvco_max = 1200000;
> > +                             fpfd_max = 450000;
> > +                     }
> > +             }
> > +             break;
> > +     case ADI_AXI_FPGA_SPEED_GRADE_XILINX_3:
> > +             fvco_max = 1600000;
> > +             fpfd_max = 550000;
> > +             break;
> > +     default:
> > +             break;
> > +     };
> > +
> > +     if (tech == ADI_AXI_FPGA_TECH_XILINX_ULTRASCALE_PLUS) {
> > +             fvco_max = 1600000;
> > +             fvco_min = 800000;
> > +     }
> > +}
> > +
> >  static int axi_clkgen_wait_non_busy(struct axi_clkgen *axi_clkgen)
> >  {
> >       unsigned int timeout = 10000;
> > @@ -524,6 +569,12 @@ static int axi_clkgen_probe(struct platform_device *pdev)
> >       if (IS_ERR(axi_clkgen->base))
> >               return PTR_ERR(axi_clkgen->base);
> >
> > +     axi_clkgen_read(axi_clkgen, ADI_AXI_REG_VERSION,
> > +                     &axi_clkgen->pcore_version);
> > +
> > +     if (ADI_AXI_PCORE_VER_MAJOR(axi_clkgen->pcore_version) > 0x04)
> > +             axi_clkgen_setup_ranges(axi_clkgen);
> > +
> >       init.num_parents = of_clk_get_parent_count(pdev->dev.of_node);
> >       if (init.num_parents < 1 || init.num_parents > 2)
> >               return -EINVAL;
> > --
> > 2.25.1
> >
> Thanks,
> Moritz