x86: apl: Add UART driver

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>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

diff --git a/arch/x86/cpu/apollolake/Makefile b/arch/x86/cpu/apollolake/Makefile
index 5e136b6515339427123e4868e4021a293b3ac414..fdda748ea352450ef9ee164bea30f51b7c12aba5 100644 (file)
--- 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 (file)
index 0000000..f2b356e
--- /dev/null
+++ b/arch/x86/cpu/apollolake/uart.c
@@ -0,0 +1,133 @@
+// 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)
+{
+#if CONFIG_IS_ENABLED(OF_PLATDATA)
+       struct dtd_intel_apl_ns16550 *dtplat = dev_get_platdata(dev);
+       struct ns16550_platdata *plat;
+
+       /*
+        * 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;
+#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 (file)
index 0000000..d4fffe6
--- /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 board_debug_uart_init() for that.
+ */
+int apl_uart_init(pci_dev_t bdf, ulong base);
+
+#endif