mirror of
https://github.com/AsahiLinux/u-boot
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74d11d37e2
This adds a serial driver which uses semihosting calls to read and write to the host's console. For convenience, if CONFIG_DM_SERIAL is enabled, we will instantiate a serial driver. This allows users to enable this driver (which has no physical device) without modifying their device trees or board files. We also implement a non-DM driver for SPL, or for much faster output in U-Boot proper. There are three ways to print to the console: Method Baud ================== ===== smh_putc in a loop 170 smh_puts 1600 smh_write with :tt 20000 ================== ===== These speeds were measured using a 175 character message with a J-Link adapter. For reference, U-Boot typically prints around 2700 characters during boot on this board. There are two major factors affecting the speed of these functions. First, each breakpoint incurs a delay. Second, each debugger memory transaction incurs a delay. smh_putc has a breakpoint and memory transaction for every character. smh_puts has one breakpoint, but still has to use a transaction for every character. This is because we don't know the length up front, so OpenOCD has to check if each character is nul. smh_write has only one breakpoint and one memory transfer. DM serial drivers can only implement a putc interface, so we are stuck with the slowest API. Non-DM drivers can implement puts, which is vastly more efficient. When the driver starts up, we try to open :tt. Since this is an extension, this may fail. If it does, we fall back to smh_puts. We don't check :semihosting-features, since there are nonconforming implementations (OpenOCD) which don't implement it (but *do* implement :tt). Some semihosting implementations (QEMU) don't handle READC properly. To work around this, we try to use open/read (much like for stdin) if possible. There is no non-blocking I/O available, so we don't implement pending. This will cause __serial_tstc to always return true. If CONFIG_SERIAL_RX_BUFFER is enabled, _serial_tstc will try and read characters forever. To avoid this, we depend on this config being disabled. Signed-off-by: Sean Anderson <sean.anderson@seco.com> Reviewed-by: Simon Glass <sjg@chromium.org>
83 lines
2.8 KiB
Makefile
83 lines
2.8 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0+
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#
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# (C) Copyright 2006-2009
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# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
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ifdef CONFIG_SPL_BUILD
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ifeq ($(CONFIG_$(SPL_TPL_)BUILD)$(CONFIG_$(SPL_TPL_)DM_SERIAL),yy)
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obj-y += serial-uclass.o
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else
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obj-y += serial.o
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endif
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else
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ifdef CONFIG_DM_SERIAL
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obj-y += serial-uclass.o
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else
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obj-y += serial.o
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endif
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endif
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ifdef CONFIG_DM_SERIAL
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obj-$(CONFIG_PL01X_SERIAL) += serial_pl01x.o
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else
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obj-$(CONFIG_PL011_SERIAL) += serial_pl01x.o
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obj-$(CONFIG_SYS_NS16550_SERIAL) += serial_ns16550.o
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endif
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obj-$(CONFIG_ALTERA_UART) += altera_uart.o
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obj-$(CONFIG_ALTERA_JTAG_UART) += altera_jtag_uart.o
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obj-$(CONFIG_AR933X_UART) += serial_ar933x.o
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obj-$(CONFIG_ARM_DCC) += arm_dcc.o
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obj-$(CONFIG_ATMEL_USART) += atmel_usart.o
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obj-$(CONFIG_BCM6345_SERIAL) += serial_bcm6345.o
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obj-$(CONFIG_COREBOOT_SERIAL) += serial_coreboot.o
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obj-$(CONFIG_CORTINA_UART) += serial_cortina.o
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obj-$(CONFIG_DEBUG_SBI_CONSOLE) += serial_sbi.o
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obj-$(CONFIG_EFI_APP) += serial_efi.o
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obj-$(CONFIG_LPC32XX_HSUART) += lpc32xx_hsuart.o
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obj-$(CONFIG_MCFUART) += serial_mcf.o
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obj-$(CONFIG_SYS_NS16550) += ns16550.o
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obj-$(CONFIG_S5P_SERIAL) += serial_s5p.o
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obj-$(CONFIG_MXC_UART) += serial_mxc.o
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obj-$(CONFIG_PXA_SERIAL) += serial_pxa.o
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obj-$(CONFIG_MESON_SERIAL) += serial_meson.o
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obj-$(CONFIG_INTEL_MID_SERIAL) += serial_intel_mid.o
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ifdef CONFIG_SPL_BUILD
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obj-$(CONFIG_ROCKCHIP_SERIAL) += serial_rockchip.o
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endif
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obj-$(CONFIG_XILINX_UARTLITE) += serial_xuartlite.o
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obj-$(CONFIG_SANDBOX_SERIAL) += sandbox.o
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obj-$(CONFIG_SCIF_CONSOLE) += serial_sh.o
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obj-$(CONFIG_SEMIHOSTING_SERIAL) += serial_semihosting.o
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obj-$(CONFIG_ZYNQ_SERIAL) += serial_zynq.o
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obj-$(CONFIG_FSL_LPUART) += serial_lpuart.o
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obj-$(CONFIG_FSL_LINFLEXUART) += serial_linflexuart.o
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obj-$(CONFIG_ARC_SERIAL) += serial_arc.o
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obj-$(CONFIG_UNIPHIER_SERIAL) += serial_uniphier.o
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obj-$(CONFIG_STM32_SERIAL) += serial_stm32.o
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obj-$(CONFIG_STI_ASC_SERIAL) += serial_sti_asc.o
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obj-$(CONFIG_PIC32_SERIAL) += serial_pic32.o
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obj-$(CONFIG_BCM283X_MU_SERIAL) += serial_bcm283x_mu.o
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obj-$(CONFIG_BCM283X_PL011_SERIAL) += serial_bcm283x_pl011.o
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obj-$(CONFIG_MSM_SERIAL) += serial_msm.o
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obj-$(CONFIG_MSM_GENI_SERIAL) += serial_msm_geni.o
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obj-$(CONFIG_MVEBU_A3700_UART) += serial_mvebu_a3700.o
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obj-$(CONFIG_MPC8XX_CONS) += serial_mpc8xx.o
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obj-$(CONFIG_NULLDEV_SERIAL) += serial_nulldev.o
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obj-$(CONFIG_OCTEON_SERIAL_BOOTCMD) += serial_octeon_bootcmd.o
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obj-$(CONFIG_OCTEON_SERIAL_PCIE_CONSOLE) += serial_octeon_pcie_console.o
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obj-$(CONFIG_OWL_SERIAL) += serial_owl.o
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obj-$(CONFIG_OMAP_SERIAL) += serial_omap.o
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obj-$(CONFIG_MTK_SERIAL) += serial_mtk.o
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obj-$(CONFIG_MT7620_SERIAL) += serial_mt7620.o
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obj-$(CONFIG_HTIF_CONSOLE) += serial_htif.o
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obj-$(CONFIG_SIFIVE_SERIAL) += serial_sifive.o
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obj-$(CONFIG_XEN_SERIAL) += serial_xen.o
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ifndef CONFIG_SPL_BUILD
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obj-$(CONFIG_USB_TTY) += usbtty.o
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endif
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