[U-Boot] [PATCH v5 085/101] x86: apl: Add UART driver

Bin Meng bmeng.cn at gmail.com
Mon Dec 2 06:26:41 CET 2019


Hi Simon,

On Mon, Nov 25, 2019 at 12:12 PM Simon Glass <sjg at chromium.org> wrote:
>
> Add a driver for the Apollo Lake UART. It uses the standard ns16550 device
> but also sets up the input clock with LPSS and supports configuration via
> of-platdata.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
> Changes in v5: None
> Changes in v4:
> - Add an extra comment to apl_uart_init()
> - Tidy up header guards
> - apollolake -> Apollo Lake
>
> Changes in v3:
> - Use the LPSS code from a separate file
>
> Changes in v2: None
>
>  arch/x86/cpu/apollolake/Makefile            |   1 +
>  arch/x86/cpu/apollolake/uart.c              | 141 ++++++++++++++++++++
>  arch/x86/include/asm/arch-apollolake/uart.h |  20 +++
>  3 files changed, 162 insertions(+)
>  create mode 100644 arch/x86/cpu/apollolake/uart.c
>  create mode 100644 arch/x86/include/asm/arch-apollolake/uart.h
>
> diff --git a/arch/x86/cpu/apollolake/Makefile b/arch/x86/cpu/apollolake/Makefile
> index 5e136b6515..fdda748ea3 100644
> --- a/arch/x86/cpu/apollolake/Makefile
> +++ b/arch/x86/cpu/apollolake/Makefile
> @@ -3,3 +3,4 @@
>  # Copyright 2019 Google LLC
>
>  obj-y += pmc.o
> +obj-y += uart.o
> diff --git a/arch/x86/cpu/apollolake/uart.c b/arch/x86/cpu/apollolake/uart.c
> new file mode 100644
> index 0000000000..1dc4d33e52
> --- /dev/null
> +++ b/arch/x86/cpu/apollolake/uart.c
> @@ -0,0 +1,141 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Special driver to handle of-platdata
> + *
> + * Copyright 2019 Google LLC
> + *
> + * Some code from coreboot lpss.c
> + */
> +
> +#include <common.h>
> +#include <dm.h>
> +#include <dt-structs.h>
> +#include <ns16550.h>
> +#include <spl.h>
> +#include <asm/io.h>
> +#include <asm/pci.h>
> +#include <asm/lpss.h>
> +
> +/* Low-power Subsystem (LPSS) clock register */
> +enum {
> +       LPSS_CLOCK_CTL_REG      = 0x200,
> +       LPSS_CNT_CLOCK_EN       = 1,
> +       LPSS_CNT_CLK_UPDATE     = 1U << 31,
> +       LPSS_CLOCK_DIV_N_SHIFT  = 16,
> +       LPSS_CLOCK_DIV_N_MASK   = 0x7fff << LPSS_CLOCK_DIV_N_SHIFT,
> +       LPSS_CLOCK_DIV_M_SHIFT  = 1,
> +       LPSS_CLOCK_DIV_M_MASK   = 0x7fff << LPSS_CLOCK_DIV_M_SHIFT,
> +
> +       /* These set the UART input clock speed */
> +       LPSS_UART_CLK_M_VAL     = 0x25a,
> +       LPSS_UART_CLK_N_VAL     = 0x7fff,
> +};
> +
> +static void lpss_clk_update(void *regs, u32 clk_m_val, u32 clk_n_val)
> +{
> +       u32 clk_sel;
> +
> +       clk_sel = clk_n_val << LPSS_CLOCK_DIV_N_SHIFT |
> +                clk_m_val << LPSS_CLOCK_DIV_M_SHIFT;
> +       clk_sel |= LPSS_CNT_CLK_UPDATE | LPSS_CNT_CLOCK_EN;
> +
> +       writel(clk_sel, regs + LPSS_CLOCK_CTL_REG);
> +}
> +
> +static void uart_lpss_init(void *regs)
> +{
> +       /* Take UART out of reset */
> +       lpss_reset_release(regs);
> +
> +       /* Set M and N divisor inputs and enable clock */
> +       lpss_clk_update(regs, LPSS_UART_CLK_M_VAL, LPSS_UART_CLK_N_VAL);
> +}
> +
> +void apl_uart_init(pci_dev_t bdf, ulong base)
> +{
> +       /* Set UART base address */
> +       pci_x86_write_config(bdf, PCI_BASE_ADDRESS_0, base, PCI_SIZE_32);
> +
> +       /* Enable memory access and bus master */
> +       pci_x86_write_config(bdf, PCI_COMMAND, PCI_COMMAND_MEMORY |
> +                            PCI_COMMAND_MASTER, PCI_SIZE_32);
> +
> +       uart_lpss_init((void *)base);
> +}
> +
> +/*
> + * This driver uses its own compatible string but almost everything else from
> + * the standard ns16550 driver. This allows us to provide an of-platdata
> + * implementation, since the platdata produced by of-platdata does not match
> + * struct ns16550_platdata.
> + *
> + * When running with of-platdata (generally TPL), the platdata is converted to
> + * something that ns16550 expects. When running withoutof-platdata (SPL, U-Boot
> + * proper), we use ns16550's ofdata_to_platdata routine.
> + */
> +
> +static int apl_ns16550_probe(struct udevice *dev)
> +{
> +       struct ns16550_platdata *plat = dev_get_platdata(dev);
> +
> +       if (!CONFIG_IS_ENABLED(PCI))
> +               apl_uart_init(plat->bdf, plat->base);
> +
> +       return ns16550_serial_probe(dev);
> +}
> +
> +static int apl_ns16550_ofdata_to_platdata(struct udevice *dev)
> +{
> +       struct ns16550_platdata *plat;
> +#if CONFIG_IS_ENABLED(OF_PLATDATA)
> +       struct dtd_intel_apl_ns16550 *dtplat = dev_get_platdata(dev);
> +
> +       /*
> +        * Convert our platdata to the ns16550's platdata, so we can just use
> +        * that driver
> +        */
> +       plat = malloc(sizeof(*plat));
> +       if (!plat)
> +               return -ENOMEM;
> +       plat->base = dtplat->early_regs[0];
> +       plat->reg_width = 1;
> +       plat->reg_shift = dtplat->reg_shift;
> +       plat->reg_offset = 0;
> +       plat->clock = dtplat->clock_frequency;
> +       plat->fcr = UART_FCR_DEFVAL;
> +       plat->bdf = pci_ofplat_get_devfn(dtplat->reg[0]);
> +       dev->platdata = plat;
> +#else
> +       int ret;
> +
> +       ret = ns16550_serial_ofdata_to_platdata(dev);
> +       if (ret)
> +               return ret;
> +       if (!CONFIG_IS_ENABLED(OF_TRANSLATE)) {
> +               /*
> +                * Without address translation we cannot get correct PCI
> +                * address, so just read the BAR manually.
> +                */

Is this a bug in the DM PCI codes?

> +               plat = dev_get_platdata(dev);
> +               plat->base = dm_pci_read_bar32(dev, 0);
> +       }
> +#endif /* OF_PLATDATA */
> +
> +       return 0;
> +}
> +
> +static const struct udevice_id apl_ns16550_serial_ids[] = {
> +       { .compatible = "intel,apl-ns16550" },
> +       { },
> +};
> +
> +U_BOOT_DRIVER(apl_ns16550) = {
> +       .name   = "intel_apl_ns16550",
> +       .id     = UCLASS_SERIAL,
> +       .of_match = apl_ns16550_serial_ids,
> +       .platdata_auto_alloc_size = sizeof(struct ns16550_platdata),
> +       .priv_auto_alloc_size = sizeof(struct NS16550),
> +       .ops    = &ns16550_serial_ops,
> +       .ofdata_to_platdata = apl_ns16550_ofdata_to_platdata,
> +       .probe = apl_ns16550_probe,
> +};
> diff --git a/arch/x86/include/asm/arch-apollolake/uart.h b/arch/x86/include/asm/arch-apollolake/uart.h
> new file mode 100644
> index 0000000000..71006ccc74
> --- /dev/null
> +++ b/arch/x86/include/asm/arch-apollolake/uart.h
> @@ -0,0 +1,20 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright 2019 Google LLC
> + */
> +
> +#ifndef _ASM_ARCH_UART_H
> +#define _ASM_ARCH_UART_H
> +
> +/**
> + * apl_uart_init() - Set up the APL UART device and clock
> + *
> + * This enables the PCI device, sets up the MMIO region and turns on the clock
> + * using LPSS.
> + *
> + * The UART won't actually work unless the GPIO settings are correct and the
> + * signals actually exit the SoC. See init_for_uart() for that.

Where is init_for_uart()?

> + */
> +int apl_uart_init(pci_dev_t bdf, ulong base);
> +
> +#endif
> --

Regards,
Bin


More information about the U-Boot mailing list