u-boot/drivers/serial/serial_intel_mid.c
Bin Meng 4687919684 serial: Remove DM_FLAG_PRE_RELOC flag in various drivers
When a driver declares DM_FLAG_PRE_RELOC flag, it wishes to be
bound before relocation. However due to a bug in the DM core,
the flag only takes effect when devices are statically declared
via U_BOOT_DEVICE(). This bug has been fixed recently by commit
"dm: core: Respect drivers with the DM_FLAG_PRE_RELOC flag in
lists_bind_fdt()", but with the fix, it has a side effect that
all existing drivers that declared DM_FLAG_PRE_RELOC flag will
be bound before relocation now. This may expose potential boot
failure on some boards due to insufficient memory during the
pre-relocation stage.

To mitigate this potential impact, the following changes are
implemented:

- Remove DM_FLAG_PRE_RELOC flag in the driver, if the driver
  only supports configuration from device tree (OF_CONTROL)
- Keep DM_FLAG_PRE_RELOC flag in the driver only if the device
  is statically declared via U_BOOT_DEVICE()
- Surround DM_FLAG_PRE_RELOC flag with OF_CONTROL check, for
  drivers that support both statically declared devices and
  configuration from device tree

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2018-11-14 09:16:28 -08:00

67 lines
1.5 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (c) 2017 Intel Corporation
*/
#include <common.h>
#include <dm.h>
#include <ns16550.h>
#include <serial.h>
/*
* The UART clock is calculated as
*
* UART clock = XTAL * UART_MUL / UART_DIV
*
* The baudrate is calculated as
*
* baud rate = UART clock / UART_PS / DLAB
*/
#define UART_PS 0x30
#define UART_MUL 0x34
#define UART_DIV 0x38
static void mid_writel(struct ns16550_platdata *plat, int offset, int value)
{
unsigned char *addr;
offset *= 1 << plat->reg_shift;
addr = (unsigned char *)plat->base + offset;
writel(value, addr + plat->reg_offset);
}
static int mid_serial_probe(struct udevice *dev)
{
struct ns16550_platdata *plat = dev_get_platdata(dev);
/*
* Initialize fractional divider correctly for Intel Edison
* platform.
*
* For backward compatibility we have to set initial DLAB value
* to 16 and speed to 115200 baud, where initial frequency is
* 29491200Hz, and XTAL frequency is 38.4MHz.
*/
mid_writel(plat, UART_MUL, 96);
mid_writel(plat, UART_DIV, 125);
mid_writel(plat, UART_PS, 16);
return ns16550_serial_probe(dev);
}
static const struct udevice_id mid_serial_ids[] = {
{ .compatible = "intel,mid-uart" },
{}
};
U_BOOT_DRIVER(serial_intel_mid) = {
.name = "serial_intel_mid",
.id = UCLASS_SERIAL,
.of_match = mid_serial_ids,
.ofdata_to_platdata = ns16550_serial_ofdata_to_platdata,
.platdata_auto_alloc_size = sizeof(struct ns16550_platdata),
.priv_auto_alloc_size = sizeof(struct NS16550),
.probe = mid_serial_probe,
.ops = &ns16550_serial_ops,
};