[PATCH v2 28/32] cpu: add basic cpu driver for MediaTek ARM chips

[Weijie Gao]

On Wed, 2022-08-31 at 07:46 -0600, Simon Glass wrote:
> Hi Weijie,
> 
> On Wed, 31 Aug 2022 at 05:08, Weijie Gao <weijie.gao at mediatek.com>
> wrote:
> > 
> > Add basic CPU driver used to retrieve CPU model information.
> > 
> > Signed-off-by: Weijie Gao <weijie.gao at mediatek.com>
> > ---
> >   v2 changes: new
> > ---
> >  drivers/cpu/Makefile  |   1 +
> >  drivers/cpu/mtk_cpu.c | 106
> > ++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 107 insertions(+)
> >  create mode 100644 drivers/cpu/mtk_cpu.c
> > 
> > diff --git a/drivers/cpu/Makefile b/drivers/cpu/Makefile
> > index 20884b1795..3b38ba9c58 100644
> > --- a/drivers/cpu/Makefile
> > +++ b/drivers/cpu/Makefile
> > @@ -9,6 +9,7 @@ obj-$(CONFIG_CPU) += cpu-uclass.o
> >  obj-$(CONFIG_ARCH_BMIPS) += bmips_cpu.o
> >  obj-$(CONFIG_ARCH_IMX8) += imx8_cpu.o
> >  obj-$(CONFIG_ARCH_AT91) += at91_cpu.o
> > +obj-$(CONFIG_ARCH_MEDIATEK) += mtk_cpu.o
> >  obj-$(CONFIG_CPU_MPC83XX) += mpc83xx_cpu.o
> >  obj-$(CONFIG_CPU_RISCV) += riscv_cpu.o
> >  obj-$(CONFIG_CPU_MICROBLAZE) += microblaze_cpu.o
> > diff --git a/drivers/cpu/mtk_cpu.c b/drivers/cpu/mtk_cpu.c
> > new file mode 100644
> > index 0000000000..d00b4c669e
> > --- /dev/null
> > +++ b/drivers/cpu/mtk_cpu.c
> > @@ -0,0 +1,106 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2022 MediaTek Inc. All rights reserved.
> > + *
> > + * Author: Weijie Gao <weijie.gao at mediatek.com>
> > + */
> > +
> > +#include <linux/types.h>
> > +#include <cpu.h>
> > +#include <dm.h>
> > +#include <fdt_support.h>
> > +#include <mapmem.h>
> > +#include <asm/global_data.h>
> > +#include <linux/io.h>
> > +
> > +DECLARE_GLOBAL_DATA_PTR;
> 
> dont't need this?
> 
> > +
> > +struct mtk_cpu_plat {
> > +       void __iomem *hwver_base;
> > +};
> > +
> > +static int mtk_cpu_get_desc(const struct udevice *dev, char *buf,
> > int size)
> > +{
> > +       struct mtk_cpu_plat *plat = dev_get_plat(dev);
> > +
> > +       snprintf(buf, size, "MediaTek MT%04X", readl(plat-
> > >hwver_base));
> > +
> > +       return 0;
> > +}
> > +
> > +static int mtk_cpu_get_count(const struct udevice *dev)
> > +{
> > +       return 1;
> > +}
> > +
> > +static int mtk_cpu_get_vendor(const struct udevice *dev, char
> > *buf, int size)
> > +{
> > +       snprintf(buf, size, "MediaTek");
> > +
> > +       return 0;
> > +}
> > +
> > +static int mtk_cpu_probe(struct udevice *dev)
> > +{
> > +       struct mtk_cpu_plat *plat = dev_get_plat(dev);
> > +       const void *fdt = gd->fdt_blob, *reg;
> > +       int offset, parent, len, na, ns;
> > +       u64 addr;
> > +
> > +       if (!fdt)
> > +               return -ENODEV;
> > +
> > +       offset = fdt_path_offset(fdt, "/hwver");
> 
> This is very strange, but you should have a driver for that node,
> e.g.
> a SYSCON driver. Then from this driver you can obtain the address
> with
> syscon_get_first_range() or similar.
> 
> > +       if (offset < 0)
> > +               return -ENODEV;
> > +
> > +       parent = fdt_parent_offset(fdt, offset);
> > +       if (parent < 0)
> > +               return -ENODEV;
> > +
> > +       na = fdt_address_cells(fdt, parent);
> > +       if (na < 1)
> > +               return -ENODEV;
> > +
> > +       ns = fdt_size_cells(gd->fdt_blob, parent);
> > +       if (ns < 0)
> > +               return -ENODEV;
> > +
> > +       reg = fdt_getprop(gd->fdt_blob, offset, "reg", &len);
> > +       if (!reg)
> > +               return -ENODEV;
> > +
> > +       if (ns)
> > +               addr = fdt_translate_address(fdt, offset, reg);
> > +       else
> > +               addr = fdt_read_number(reg, na);
> > +
> 
> All of the above should go away. We should use dev_read() / ofnode...
> for device tree access.

OK. This is indeed tricky. I just didn't want to add reference to the
hwver node for every cpu node.
I'll change this using the regular way.

> 
> > +       plat->hwver_base = map_sysmem(addr, 0);
> > +       if (!plat->hwver_base)
> > +               return -EINVAL;
> > +
> > +       return 0;
> > +}
> > +
> > +static const struct cpu_ops mtk_cpu_ops = {
> > +       .get_desc       = mtk_cpu_get_desc,
> > +       .get_count      = mtk_cpu_get_count,
> > +       .get_vendor     = mtk_cpu_get_vendor,
> > +};
> > +
> > +static const struct udevice_id mtk_cpu_ids[] = {
> > +       { .compatible = "arm,cortex-a7" },
> > +       { .compatible = "arm,cortex-a53" },
> > +       { .compatible = "arm,cortex-a73" },
> > +       { /* sentinel */ }
> > +};
> > +
> > +U_BOOT_DRIVER(cpu_mtk) = {
> > +       .name           = "mtk-cpu",
> > +       .id             = UCLASS_CPU,
> > +       .of_match       = mtk_cpu_ids,
> > +       .ops            = &mtk_cpu_ops,
> > +       .probe          = mtk_cpu_probe,
> > +       .plat_auto      = sizeof(struct mtk_cpu_plat),
> > +       .flags          = DM_FLAG_PRE_RELOC,
> > +};
> > --
> > 2.17.1
> > 
> 
> Regards,
> Simon