1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Special driver to handle of-platdata
4 *
5 * Copyright 2019 Google LLC
6 *
7 * Some code from coreboot lpss.c
8 */
9
10 #include <common.h>
11 #include <dm.h>
12 #include <dt-structs.h>
13 #include <malloc.h>
14 #include <ns16550.h>
15 #include <spl.h>
16 #include <asm/io.h>
17 #include <asm/pci.h>
18 #include <asm/lpss.h>
19 #include <dm/device-internal.h>
20 #include <asm/arch/uart.h>
21
22 /* Low-power Subsystem (LPSS) clock register */
23 enum {
24 LPSS_CLOCK_CTL_REG = 0x200,
25 LPSS_CNT_CLOCK_EN = 1,
26 LPSS_CNT_CLK_UPDATE = 1U << 31,
27 LPSS_CLOCK_DIV_N_SHIFT = 16,
28 LPSS_CLOCK_DIV_N_MASK = 0x7fff << LPSS_CLOCK_DIV_N_SHIFT,
29 LPSS_CLOCK_DIV_M_SHIFT = 1,
30 LPSS_CLOCK_DIV_M_MASK = 0x7fff << LPSS_CLOCK_DIV_M_SHIFT,
31
32 /* These set the UART input clock speed */
33 LPSS_UART_CLK_M_VAL = 0x25a,
34 LPSS_UART_CLK_N_VAL = 0x7fff,
35 };
36
lpss_clk_update(void * regs,u32 clk_m_val,u32 clk_n_val)37 static void lpss_clk_update(void *regs, u32 clk_m_val, u32 clk_n_val)
38 {
39 u32 clk_sel;
40
41 clk_sel = clk_n_val << LPSS_CLOCK_DIV_N_SHIFT |
42 clk_m_val << LPSS_CLOCK_DIV_M_SHIFT;
43 clk_sel |= LPSS_CNT_CLK_UPDATE | LPSS_CNT_CLOCK_EN;
44
45 writel(clk_sel, regs + LPSS_CLOCK_CTL_REG);
46 }
47
uart_lpss_init(void * regs)48 static void uart_lpss_init(void *regs)
49 {
50 /* Take UART out of reset */
51 lpss_reset_release(regs);
52
53 /* Set M and N divisor inputs and enable clock */
54 lpss_clk_update(regs, LPSS_UART_CLK_M_VAL, LPSS_UART_CLK_N_VAL);
55 }
56
apl_uart_init(pci_dev_t bdf,ulong base)57 void apl_uart_init(pci_dev_t bdf, ulong base)
58 {
59 /* Set UART base address */
60 pci_x86_write_config(bdf, PCI_BASE_ADDRESS_0, base, PCI_SIZE_32);
61
62 /* Enable memory access and bus master */
63 pci_x86_write_config(bdf, PCI_COMMAND, PCI_COMMAND_MEMORY |
64 PCI_COMMAND_MASTER, PCI_SIZE_32);
65
66 uart_lpss_init((void *)base);
67 }
68
69 /*
70 * This driver uses its own compatible string but almost everything else from
71 * the standard ns16550 driver. This allows us to provide an of-platdata
72 * implementation, since the platdata produced by of-platdata does not match
73 * struct apl_ns16550_plat.
74 *
75 * When running with of-platdata (generally TPL), the platdata is converted to
76 * something that ns16550 expects. When running withoutof-platdata (SPL, U-Boot
77 * proper), we use ns16550's of_to_plat routine.
78 */
79
apl_ns16550_probe(struct udevice * dev)80 static int apl_ns16550_probe(struct udevice *dev)
81 {
82 struct apl_ns16550_plat *plat = dev_get_plat(dev);
83
84 if (!CONFIG_IS_ENABLED(PCI))
85 apl_uart_init(plat->ns16550.bdf, plat->ns16550.base);
86
87 return ns16550_serial_probe(dev);
88 }
89
apl_ns16550_of_to_plat(struct udevice * dev)90 static int apl_ns16550_of_to_plat(struct udevice *dev)
91 {
92 #if CONFIG_IS_ENABLED(OF_PLATDATA)
93 struct dtd_intel_apl_ns16550 *dtplat;
94 struct apl_ns16550_plat *plat = dev_get_plat(dev);
95 struct ns16550_plat ns;
96
97 /*
98 * The device's plat uses struct apl_ns16550_plat which starts with the
99 * dtd struct, but the ns16550 driver expects it to be struct ns16550.
100 * Set up what that driver expects. Note that this means that the values
101 * cannot be read in this driver when using of-platdata.
102 *
103 * TODO(sjg@chromium.org): Consider having a separate plat pointer for
104 * of-platdata so that it is not necessary to overwrite this.
105 */
106 dtplat = &plat->dtplat;
107 ns.base = dtplat->early_regs[0];
108 ns.reg_width = 1;
109 ns.reg_shift = dtplat->reg_shift;
110 ns.reg_offset = 0;
111 ns.clock = dtplat->clock_frequency;
112 ns.fcr = UART_FCR_DEFVAL;
113 ns.bdf = pci_ofplat_get_devfn(dtplat->reg[0]);
114 memcpy(plat, &ns, sizeof(ns));
115 #else
116 int ret;
117
118 ret = ns16550_serial_of_to_plat(dev);
119 if (ret)
120 return ret;
121 #endif /* OF_PLATDATA */
122
123 return 0;
124 }
125
126 #if !CONFIG_IS_ENABLED(OF_PLATDATA)
127 static const struct udevice_id apl_ns16550_serial_ids[] = {
128 { .compatible = "intel,apl-ns16550" },
129 { },
130 };
131 #endif
132
133 U_BOOT_DRIVER(intel_apl_ns16550) = {
134 .name = "intel_apl_ns16550",
135 .id = UCLASS_SERIAL,
136 .of_match = of_match_ptr(apl_ns16550_serial_ids),
137 .plat_auto = sizeof(struct apl_ns16550_plat),
138 .priv_auto = sizeof(struct ns16550),
139 .ops = &ns16550_serial_ops,
140 .of_to_plat = apl_ns16550_of_to_plat,
141 .probe = apl_ns16550_probe,
142 };
143