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

[Simon Glass]

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.

> +       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