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@chromium.org ---
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. + */ + 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. + */ +int apl_uart_init(pci_dev_t bdf, ulong base); + +#endif