作者信息
作者: 彭東林
QQ：405728433
平臺簡介
開發板：tiny4412ADK + S700 + 4GB Flash
要移植的內核版本：Linux-4.4.0 （支持device tree）
u-boot版本：友善之臂自帶的 U-Boot 2010.12 （為支持uImage啟動，做了少許改動）
busybox版本：busybox 1.25
SD卡：Kingston SDHC 4GB
交叉編譯工具鏈： arm-none-linux-gnueabi-gcc
（gcc version 4.8.3 20140320 (prerelease) (Sourcery CodeBench Lite 2014.05-29)）
概述
移植SD卡比較簡單，但是剛開始的時候也出現了不少問題，關鍵是對設備樹的修改、對regulator的理解以及sdcard檢測過程。
移植
下麵是tiny4412關於sd卡部分的原理圖：
底板：
核心板：
從原理圖可以看出，tiny4412用的MMC控制器是SDMMC2。一共用到了7個引腳（CLK、CMD、CDn、DATA0-DATA3），其中CDn的意思是當插入SD卡時，這個引腳的電平會被拉低（可以輪詢這個引腳的電平轉態或者通過設置這個引腳產生中斷來檢測sdcard狀態）。在之前的移植中我們將sdhc2給disabled了：
arch/arm/boot/dts/exynos4412-tiny4412.dts：
&sdhci_2 { bus-width = <4>; pinctrl-0 = <&sd2_clk &sd2_cmd &sd2_cd &sd2_bus4>; pinctrl-names = "default"; status = "disabled"; };其中princtrl-0後的作用是設置用到的GPIO的復用功能（一旦復用為sdcard控制器的專用引腳後，就不能作為普通的gpio使用了），這幾個標號是在arch/arm/boot/dts/exynos4x12-pinctrl.dtsi中定義的：
sd2_clk: sd2-clk {
samsung,pins = "gpk2-0";
samsung,pin-function = <2>;
samsung,pin-pud = <0>;
samsung,pin-drv = <3>;
};
sd2_cmd: sd2-cmd {
samsung,pins = "gpk2-1";
samsung,pin-function = <2>;
samsung,pin-pud = <0>;
samsung,pin-drv = <3>;
};
sd2_cd: sd2-cd {
samsung,pins = "gpk2-2";
samsung,pin-function = <2>;
samsung,pin-pud = <3>;
samsung,pin-drv = <3>;
};
sd2_bus4: sd2-bus-width4 {
samsung,pins = "gpk2-3", "gpk2-4", "gpk2-5", "gpk2-6";
samsung,pin-function = <2>;
samsung,pin-pud = <3>;
samsung,pin-drv = <3>;
};
這樣只是設置了這幾個GPIO的復用功能,並不用在驅動程式中申請這幾個GPIO資源,因為這幾個引腳已經不是作為普通的GPIO使用了。
如果直接將sdhc2使能的話：
--- a/arch/arm/boot/dts/exynos4412-tiny4412.dts
+++ b/arch/arm/boot/dts/exynos4412-tiny4412.dts
@@ -86,7 +86,7 @@
bus-width = <4>;
pinctrl-0 = <&sd2_clk &sd2_cmd &sd2_cd &sd2_bus4>;
pinctrl-names = "default";
- status = "disabled";
+ status = "okay";
};
&serial_0 {
內核在啟動時會崩潰，信息如下：
1: [ 2.228406] sdhci: Secure Digital Host Controller Interface driver
2: [ 2.233751] sdhci: Copyright(c) Pierre Ossman
3: [ 2.238350] s3c-sdhci 12530000.sdhci: clock source 2: mmc_busclk.2 (100000000 Hz)
4: [ 2.245838] s3c-sdhci 12530000.sdhci: No vmmc regulator found
5: [ 2.251358] s3c-sdhci 12530000.sdhci: No vqmmc regulator found
6: [ 2.257480] ------------[ cut here ]------------
7: [ 2.261686] kernel BUG at drivers/mmc/host/sdhci.c:1304!
8: [ 2.266981] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
9: [ 2.272796] Modules linked in:
10: [ 2.275836] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0-gbd7378b-dirty #33
11: [ 2.283038] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
12: [ 2.289115] task: ef078000 ti: ef080000 task.ti: ef080000
13: [ 2.294500] PC is at sdhci_do_set_ios+0x564/0x5e0
14: [ 2.299189] LR is at arm_heavy_mb+0x1c/0x38
15: [ 2.303351] pc : [<c0406f38>] lr : [<c00198b0>] psr: 80000093
16: [ 2.303351] sp : ef081cc8 ip : 00000200 fp : 00000001
17: [ 2.314807] r10: 00000003 r9 : ef30e800 r8 : 60000013
18: [ 2.320015] r7 : ef30e800 r6 : ef30ec98 r5 : ef30ea34 r4 : ef30eb80
19: [ 2.326525] r3 : 00000001 r2 : 75004180 r1 : 00000000 r0 : ef30eb80
20: [ 2.333036] Flags: Nzcv IRQs off FIQs on Mode SVC_32 ISA ARM Segment none
21: [ 2.340240] Control: 10c5387d Table: 4000404a DAC: 00000051
22: [ 2.345969] Process swapper/0 (pid: 1, stack limit = 0xef080210)
23: [ 2.351958] Stack: (0xef081cc8 to 0xef082000)
24: [ 2.356300] 1cc0: 00000000 ef30eb80 00000043 c02d30e8 c02d30e8 00000004
25: [ 2.364460] 1ce0: c0058b5c ef080000 ef1a6ebc c0407168 ef1a6e10 ef1a6e80 c02d30e8 c02d3114
26: [ 2.372619] 1d00: 00000004 c02d465c ef1a6e10 c0852100 c086ea10 c02d46b0 00000000 ef1a6e10
27: [ 2.380778] 1d20: c0852100 c02d54fc eeca0fa0 c00f2934 00000188 eeca0fa0 ef078000 60000013
28: [ 2.388937] 1d40: ef1a6e80 ef1a6e10 ef1a6e80 00000004 60000013 00000000 00000002 ef30ea80
29: [ 2.397096] 1d60: 00000000 c02d56c8 00000000 ef30e800 ef30ea24 60000013 ef080000 c03eff80
30: [ 2.405256] 1d80: eec0b7b8 00000000 ef078000 c0044ee8 00000100 00000200 eec0b6b4 ef30e800
31: [ 2.413415] 1da0: ef30ed2c ef30eb80 ef30e800 00000000 00000200 00000000 ef30ed18 c03f2fd8
32: [ 2.421574] 1dc0: ef30e800 c03f41ac 00000000 c0407ba4 ef264300 ef30eb80 00000808 ef30e800
33: [ 2.429733] 1de0: ef7d3488 00000000 00000000 c03f3dd4 00000000 ef30eb80 00000004 ef1a6e10
34: [ 2.437893] 1e00: ef1a6e00 ef30edec 00000001 ef264110 00000000 c0408be8 05f5e100 c087a810
35: [ 2.446052] 1e20: ef17df50 c087a8a4 5f636d6d 63737562 332e6b6c ee9d9600 00000001 ef1a6e10
36: [ 2.454211] 1e40: fffffffe fffffdfb c087a810 c087a810 00000000 c081683c c0816848 c02ce238
37: [ 2.462370] 1e60: c02ce1e8 ef1a6e10 c08d942c c088e410 00000000 c02cc634 c087a810 ef1a6e44
38: [ 2.470529] 1e80: c088e338 ef1a6e10 c087a810 ef1a6e44 c088e338 00000000 00000000 c02cc8d4
39: [ 2.478688] 1ea0: 00000000 c087a810 c02cc848 c02ca7d4 ef003274 ef17b7c0 c087a810 eebf6f00
40: [ 2.486848] 1ec0: c086ebc8 c02cbb48 c0755dc0 c087a810 c087a810 c0855520 ef267240 c089c000
41: [ 2.495007] 1ee0: c08023cc c02cd0cc c087a7fc c0855520 c0855520 c00097a0 ef15eb00 c0598680
42: [ 2.503166] 1f00: 00000025 0000c000 ef078000 60000013 efffca92 c05aba2c 000000c0 c003da88
43: [ 2.511325] 1f20: 00000001 00000003 c0746c3c c07b1804 00000000 c088c6b8 00000006 00000006
44: [ 2.519484] 1f40: c0858ec8 c0849e3c c084a108 00000006 c089c000 c089c000 c07e35b0 000000c0
45: [ 2.527643] 1f60: c081683c c07e3dec 00000006 00000006 00000000 c07e35b0 ef078000 c0042518
46: [ 2.535802] 1f80: 000000a2 00000000 c058e6c8 00000000 00000000 00000000 00000000 00000000
47: [ 2.543962] 1fa0: 00000000 c058e6d0 00000000 c0010338 00000000 00000000 00000000 00000000
48: [ 2.552121] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
49: [ 2.560280] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000 dffffefb f5fbff7f
50: [ 2.568447] [<c0406f38>] (sdhci_do_set_ios) from [<c0407168>] (sdhci_runtime_resume_host+0x60/0x114)
51: [ 2.577557] [<c0407168>] (sdhci_runtime_resume_host) from [<c02d3114>] (pm_generic_runtime_resume+0x2c/0x38)
52: [ 2.587366] [<c02d3114>] (pm_generic_runtime_resume) from [<c02d465c>] (__rpm_callback+0x2c/0x60)
53: [ 2.596216] [<c02d465c>] (__rpm_callback) from [<c02d46b0>] (rpm_callback+0x20/0x80)
54: [ 2.603942] [<c02d46b0>] (rpm_callback) from [<c02d54fc>] (rpm_resume+0x3ac/0x52c)
55: [ 2.611493] [<c02d54fc>] (rpm_resume) from [<c02d56c8>] (__pm_runtime_resume+0x4c/0x64)
56: [ 2.619482] [<c02d56c8>] (__pm_runtime_resume) from [<c03eff80>] (__mmc_claim_host+0x190/0x19c)
57: [ 2.628161] [<c03eff80>] (__mmc_claim_host) from [<c03f2fd8>] (mmc_start_host+0x38/0x98)
58: [ 2.636232] [<c03f2fd8>] (mmc_start_host) from [<c03f41ac>] (mmc_add_host+0x58/0x7c)
59: [ 2.643957] [<c03f41ac>] (mmc_add_host) from [<c0407ba4>] (sdhci_add_host+0x988/0xe80)
60: [ 2.651855] [<c0407ba4>] (sdhci_add_host) from [<c0408be8>] (sdhci_s3c_probe+0x4a8/0x548)
61: [ 2.660016] [<c0408be8>] (sdhci_s3c_probe) from [<c02ce238>] (platform_drv_probe+0x50/0xac)
62: [ 2.668348] [<c02ce238>] (platform_drv_probe) from [<c02cc634>] (driver_probe_device+0x240/0x454)
63: [ 2.677200] [<c02cc634>] (driver_probe_device) from [<c02cc8d4>] (__driver_attach+0x8c/0x90)
64: [ 2.685626] [<c02cc8d4>] (__driver_attach) from [<c02ca7d4>] (bus_for_each_dev+0x60/0x94)
65: [ 2.693780] [<c02ca7d4>] (bus_for_each_dev) from [<c02cbb48>] (bus_add_driver+0x1b8/0x26c)
66: [ 2.702025] [<c02cbb48>] (bus_add_driver) from [<c02cd0cc>] (driver_register+0x78/0xf8)
67: [ 2.710012] [<c02cd0cc>] (driver_register) from [<c00097a0>] (do_one_initcall+0xbc/0x1f4)
68: [ 2.718176] [<c00097a0>] (do_one_initcall) from [<c07e3dec>] (kernel_init_freeable+0x158/0x1f8)
69: [ 2.726855] [<c07e3dec>] (kernel_init_freeable) from [<c058e6d0>] (kernel_init+0x8/0xf0)
70: [ 2.734927] [<c058e6d0>] (kernel_init) from [<c0010338>] (ret_from_fork+0x14/0x3c)
71: [ 2.742474] Code: e3510000 05991010 ebf24b35 eaffff77 (e7f001f2)
72: [ 2.748557] ---[ end trace 6068c23e2cfdffe9 ]---
73: [ 2.753149] note: swapper/0[1] exited with preempt_count 1
74: [ 2.758738] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
75: [ 2.758738]
76: [ 2.767732] CPU1: stopping
77: [ 2.770423] CPU: 1 PID: 0 Comm: swapper/1 Tainted: G D 4.4.0-gbd7378b-dirty #33
78: [ 2.778840] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
79: [ 2.784927] [<c0016fc0>] (unwind_backtrace) from [<c0013ab8>] (show_stack+0x10/0x14)
80: [ 2.792652] [<c0013ab8>] (show_stack) from [<c01fa9d8>] (dump_stack+0x80/0xc0)
81: [ 2.799851] [<c01fa9d8>] (dump_stack) from [<c0016030>] (handle_IPI+0x1ac/0x1c0)
82: [ 2.807227] [<c0016030>] (handle_IPI) from [<c00094d0>] (gic_handle_irq+0x90/0x94)
83: [ 2.814778] [<c00094d0>] (gic_handle_irq) from [<c0014594>] (__irq_svc+0x54/0x90)
84: [ 2.822240] Exception stack(0xef0aff88 to 0xef0affd0)
85: [ 2.827277] ff80: 00000001 00000000 ef0affe0 c001c860 c05977c8 00000000
86: [ 2.835437] ffa0: 00000000 c084e3c0 c08524b4 c084b2e4 ef0ae000 c08524bc 00000001 ef0affd8
87: [ 2.843594] ffc0: c0010da8 c0010dac 60000013 ffffffff
88: [ 2.848631] [<c0014594>] (__irq_svc) from [<c0010dac>] (arch_cpu_idle+0x38/0x3c)
89: [ 2.856015] [<c0010dac>] (arch_cpu_idle) from [<c0059018>] (cpu_startup_entry+0x1b0/0x26c)
90: [ 2.864256] [<c0059018>] (cpu_startup_entry) from [<4000956c>] (0x4000956c)
91: [ 2.871196] CPU3: stopping
92: [ 2.873888] CPU: 3 PID: 0 Comm: swapper/3 Tainted: G D 4.4.0-gbd7378b-dirty #33
93: [ 2.882305] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
94: [ 2.888389] [<c0016fc0>] (unwind_backtrace) from [<c0013ab8>] (show_stack+0x10/0x14)
95: [ 2.896113] [<c0013ab8>] (show_stack) from [<c01fa9d8>] (dump_stack+0x80/0xc0)
96: [ 2.903315] [<c01fa9d8>] (dump_stack) from [<c0016030>] (handle_IPI+0x1ac/0x1c0)
97: [ 2.910692] [<c0016030>] (handle_IPI) from [<c00094d0>] (gic_handle_irq+0x90/0x94)
98: [ 2.918243] [<c00094d0>] (gic_handle_irq) from [<c0014594>] (__irq_svc+0x54/0x90)
99: [ 2.925706] Exception stack(0xef0b3f88 to 0xef0b3fd0)
100: [ 2.930743] 3f80: 00000001 00000000 ef0b3fe0 c001c860 c05977c8 00000000
101: [ 2.938902] 3fa0: 00000000 c084e3c0 c08524b4 c084b2e4 ef0b2000 c08524bc 00000001 ef0b3fd8
102: [ 2.947060] 3fc0: c0010da8 c0010dac 60000013 ffffffff
103: [ 2.952096] [<c0014594>] (__irq_svc) from [<c0010dac>] (arch_cpu_idle+0x38/0x3c)
104: [ 2.959476] [<c0010dac>] (arch_cpu_idle) from [<c0059018>] (cpu_startup_entry+0x1b0/0x26c)
105: [ 2.967720] [<c0059018>] (cpu_startup_entry) from [<4000956c>] (0x4000956c)
106: [ 2.974661] CPU2: stopping
107: [ 2.977354] CPU: 2 PID: 0 Comm: swapper/2 Tainted: G D 4.4.0-gbd7378b-dirty #33
108: [ 2.985771] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
109: [ 2.991854] [<c0016fc0>] (unwind_backtrace) from [<c0013ab8>] (show_stack+0x10/0x14)
110: [ 2.999578] [<c0013ab8>] (show_stack) from [<c01fa9d8>] (dump_stack+0x80/0xc0)
111: [ 3.006781] [<c01fa9d8>] (dump_stack) from [<c0016030>] (handle_IPI+0x1ac/0x1c0)
112: [ 3.014158] [<c0016030>] (handle_IPI) from [<c00094d0>] (gic_handle_irq+0x90/0x94)
113: [ 3.021709] [<c00094d0>] (gic_handle_irq) from [<c0014594>] (__irq_svc+0x54/0x90)
114: [ 3.029171] Exception stack(0xef0b1f88 to 0xef0b1fd0)
115: [ 3.034208] 1f80: 00000001 00000000 ef0b1fe0 c001c860 c05977c8 00000000
116: [ 3.042368] 1fa0: 00000000 c084e3c0 c08524b4 c084b2e4 ef0b0000 c08524bc 00000001 ef0b1fd8
117: [ 3.050525] 1fc0: c0010da8 c0010dac 60000013 ffffffff
118: [ 3.055562] [<c0014594>] (__irq_svc) from [<c0010dac>] (arch_cpu_idle+0x38/0x3c)
119: [ 3.062942] [<c0010dac>] (arch_cpu_idle) from [<c0059018>] (cpu_startup_entry+0x1b0/0x26c)
120: [ 3.071185] [<c0059018>] (cpu_startup_entry) from [<4000956c>] (0x4000956c)
121: [ 3.078130] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
122: [ 3.078130]
在第4和第5行可以看到：
[ 2.245838] s3c-sdhci 12530000.sdhci: No vmmc regulator found [ 2.251358] s3c-sdhci 12530000.sdhci: No vqmmc regulator found
再結合列印出的棧信息，可以確定就是由於沒有為sdhc2設置vmmc或者vqmmc導致的，這兩個是關於regulator的，但是從開發板的原理圖上看到，sdcard這部分的供電完全是在設計原理圖時就固定死了，根本不需要什麼regulator，但是經過分析drivers/mmc/host/sdhci-s3c.c文件中host的註冊過程，還必須設置regulator信息。通過對比其他平臺的設備樹文件（主要是：arch/arm/boot/dts/exynos4412-origen.dts和arch/arm/boot/dts/exynos4412-trats2.dts），我對tiny4412的設備樹文件進行瞭如下修改：
1: diff --git a/arch/arm/boot/dts/exynos4412-tiny4412.dts b/arch/arm/boot/dts/exynos4412-tiny4412.dts
2: index 69a0d5d..b82e303 100644
3: --- a/arch/arm/boot/dts/exynos4412-tiny4412.dts
4: +++ b/arch/arm/boot/dts/exynos4412-tiny4412.dts
5: @@ -75,7 +75,21 @@
6: compatible = "smsc,usb4640";
7: reset-gpios = <&gpm2 4 GPIO_ACTIVE_LOW>;
8: initial-mode = <USB4640_MODE_HUB>;
9: - };
10: + };
11: +
12: + regulators {
13: + compatible = "simple-bus";
14: + #address-cells = <1>;
15: + #size-cells = <0>;
16: +
17: + mmc_reg: regulator@0{
18: + compatible = "regulator-fixed";
19: + reg = <0>;
20: + regulator-name = "VMEM_VDD_2.8V";
21: + regulator-min-microvolt = <2800000>;
22: + regulator-max-microvolt = <2800000>;
23: + };
24: + };
25: };
26:
27: &rtc {
28: @@ -86,7 +100,10 @@
29: bus-width = <4>;
30: pinctrl-0 = <&sd2_clk &sd2_cmd &sd2_cd &sd2_bus4>;
31: pinctrl-names = "default";
32: - status = "disabled";
33: + vmmc-supply = <&mmc_reg>;
34: + cd-gpios = <&gpk2 2 GPIO_ACTIVE_HIGH>;
35: + cd-inverted;
36: + status = "okay";
37: };
38:
39: &serial_0 {
在參考文件arch/arm/boot/dts/exynos4412-origen.dts中的mmc_reg配置中：
1: regulators {
2: compatible = "simple-bus";
3: #address-cells = <1>;
4: #size-cells = <0>;
5:
6: mmc_reg: regulator@0 {
7: compatible = "regulator-fixed";
8: reg = <0>;
9: regulator-name = "VMEM_VDD_2.8V";
10: regulator-min-microvolt = <2800000>;
11: regulator-max-microvolt = <2800000>;
12: gpio = <&gpx1 1 GPIO_ACTIVE_HIGH>;
13: enable-active-high;
14: };
15: };
可以看到，origen平臺還配置有gpio資源（應該是用於控制板子上的某個LDO晶元的開關，目的是給sdcard供電，在開始測試的時候發現，如果也給tiny4412配置上gpio的話，在插入sdcard會，這個gpio電平會被控制器拉高，當拔出sdcard後，這個gpio的電平會被拉低，證明瞭我的猜想。感覺tiny4412做的有點不好的是板子上沒有PMIC，因此不利於學習電源管理，因為一般的手機或者平板產品上都是有PMIC的），但是我們的tiny4412並不需要，所以我把gpio屬性刪去了，這裡的電壓2800000不要亂動，儘管對於tiny4412沒什麼用，但是如果設置不當，在內核啟動log中會列印錯誤信息。
還要說明的一點是：
1: cd-gpios = <&gpk2 2 GPIO_ACTIVE_HIGH>;
2: cd-inverted;
cd-gpios用於設置sdcard插入拔出檢測引腳，從原理圖中可以看到tiny4412的sdcard檢測引腳(Xmmc2CDn)使用的是GPIOK2_2，這樣在註冊sd卡控制器(drivers/mmc/host/sdhci-s3c.c[sdhci_s3c_probe->sdhci_add_host]、drivers/mmc/host/sdhci.c[sdhci_add_host->mmc_add_host]、drivers/mmc/core/host.c[mmc_add_host->mmc_start_host]、drivers/mmc/core/core.c[mmc_start_host -> mmc_gpiod_request_cd_irg]、drivers/mmc/core/slot-gpio.c[mmc_gpiod_request_cd_irq])的時候就會在這個引腳上申請一個中斷資源（實際中發現觸發類型是上下沿觸發 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT ），如果這裡設置了用gpio中斷檢測sdcard狀態的屬性，就可以把
pinctrl-0 = <&sd2_clk &sd2_cmd &sd2_cd &sd2_bus4>;
改為
pinctrl-0 = <&sd2_clk &sd2_cmd &sd2_bus4>;
即刪除對sdcard檢測引腳的功能復用的設置，即不需要sdcard控制器這個硬體（結合exynos4412的用戶手冊發現，也需要驅動程式的配合才行）來檢測sdcard狀態。此時的patch如下：
1: diff --git a/arch/arm/boot/dts/exynos4412-tiny4412.dts b/arch/arm/boot/dts/exynos4412-tiny4412.dts
2: index 69a0d5d..bd823eb 100644
3: --- a/arch/arm/boot/dts/exynos4412-tiny4412.dts
4: +++ b/arch/arm/boot/dts/exynos4412-tiny4412.dts
5: @@ -75,7 +75,21 @@
6: compatible = "smsc,usb4640";
7: reset-gpios = <&gpm2 4 GPIO_ACTIVE_LOW>;
8: initial-mode = <USB4640_MODE_HUB>;
9: - };
10: + };
11: +
12: + regulators {
13: + compatible = "simple-bus";
14: + #address-cells = <1>;
15: + #size-cells = <0>;
16: +
17: + mmc_reg: regulator@0{
18: + compatible = "regulator-fixed";
19: + reg = <0>;
20: + regulator-name = "VMEM_VDD_2.8V";
21: + regulator-min-microvolt = <2800000>;
22: + regulator-max-microvolt = <2800000>;
23: + };
24: + };
25: };
26:
27: &rtc {
28: @@ -84,9 +98,12 @@
29:
30: &sdhci_2 {
31: bus-width = <4>;
32: - pinctrl-0 = <&sd2_clk &sd2_cmd &sd2_cd &sd2_bus4>;
33: + pinctrl-0 = <&sd2_clk &sd2_cmd &sd2_bus4>;
34: pinctrl-names = "default";
35: - status = "disabled";
36: + vmmc-supply = <&mmc_reg>;
37: + cd-gpios = <&gpk2 2 GPIO_ACTIVE_HIGH>;
38: + cd-inverted;
39: + status = "okay";
40: };
41:
42: &serial_0 {
在測試時發現，如果使用sdcard控制器內部檢測sdcard狀態，那麼在發生sdcard插拔動作時，Linux系統並不能識別到，不知道是不是Samsung的SDMMC控制器驅動的問題，這個得以後看看，此時的patch如下：
1: diff --git a/arch/arm/boot/dts/exynos4412-tiny4412.dts b/arch/arm/boot/dts/exynos4412-tiny4412.dts
2: index 69a0d5d..ad8b2ba 100644
3: --- a/arch/arm/boot/dts/exynos4412-tiny4412.dts
4: +++ b/arch/arm/boot/dts/exynos4412-tiny4412.dts
5: @@ -75,7 +75,21 @@
6: compatible = "smsc,usb4640";
7: reset-gpios = <&gpm2 4 GPIO_ACTIVE_LOW>;
8: initial-mode = <USB4640_MODE_HUB>;
9: - };
10: + };
11: +
12: + regulators {
13: + compatible = "simple-bus";
14: + #address-cells = <1>;
15: + #size-cells = <0>;
16: +
17: + mmc_reg: regulator@0{
18: + compatible = "regulator-fixed";
19: + reg = <0>;
20: + regulator-name = "VMEM_VDD_2.8V";
21: + regulator-min-microvolt = <2800000>;
22: + regulator-max-microvolt = <2800000>;
23: + };
24: + };
25: };
26:
27: &rtc {
28: @@ -86,7 +100,8 @@
29: bus-width = <4>;
30: pinctrl-0 = <&sd2_clk &sd2_cmd &sd2_cd &sd2_bus4>;
31: pinctrl-names = "default";
32: - status = "disabled";
33: + vmmc-supply = <&mmc_reg>;
34: + status = "okay";
35: };
36:
37: &serial_0 {
可以下麵的兩個參考文件，其中對設置mmc控制器的設備樹屬性進行了介紹。
Documentation/devicetree/bindings/mmc/samsung-sdhci.txt
Documentation/devicetree/bindings/mmc/mmc.txt
下麵是Linux啟動時檢測到sdcard的log：
1: [ 2.238481] s3c-sdhci 12530000.sdhci: clock source 2: mmc_busclk.2 (100000000 Hz)
2: [ 2.245749] s3c-sdhci 12530000.sdhci: Got CD GPIO
3: [ 2.250721] s3c-sdhci 12530000.sdhci: No vqmmc regulator found
4: [ 2.285341] mmc0: SDHCI controller on samsung-hsmmc [12530000.sdhci] using ADMA
5: [ 2.285548] Synopsys Designware Multimedia Card Interface Driver
6: [ 2.287669] usbcore: registered new interface driver usbhid
7: [ 2.287723] usbhid: USB HID core driver
8: [ 2.290841] NET: Registered protocol family 10
9: [ 2.291451] sit: IPv6 over IPv4 tunneling driver
10: [ 2.295264] NET: Registered protocol family 17
11: [ 2.299165] NET: Registered protocol family 15
12: [ 2.303746] Registering SWP/SWPB emulation handler
13: [ 2.309720] hctosys: unable to open rtc device (rtc0)
14: [ 2.325428] ALSA device list:
15: [ 2.325464] No soundcards found.
16: [ 2.326127] RAMDISK: gzip image found at block 0
17: [ 2.360265] usb 2-2: new high-speed USB device number 2 using exynos-ehci
18: [ 2.468324] EXT4-fs (ram0): mounted filesystem witdered data mode. Opts: (null)
19: [ 2.468418] VFS: Mounted root (ext4 filesystem) on device 1:0.
20: [ 2.468545] devtmpfs: mounted
21: [ 2.468819] Freeing unused kernel memory: 436K (c07e3000 - c0850000)
22: [ 2.490598] usb 2-2: New USB device found, idVendor=0424, idProduct=2640
23: [ 2.490671] usb 2-2: New USB device strings: Mfr=0, Product=0, SerialNumber=0
24: [ 2.491880] hub 2-2:1.0: USB hub found
25: [ 2.492094] hub 2-2:1.0: 3 ports detected
26: [ 2.519078] mmc0: new high speed SDHC card at address b368
27: [ 2.524690] mmcblk0: mmc0:b368 SMI 3.71 GiB
28: [ 2.526964] mmcblk0: p1
查看系統gpio資源分配情況
[root@tiny4412 ]# cat /sys/kernel/debug/gpio ...... GPIOs 90-96, platform/11000000.pinctrl, gpk1: GPIOs 97-103, platform/11000000.pinctrl, gpk2: gpio-99 ( |cd ) in lo IRQ ...... GPIOs 143-147, platform/11000000.pinctrl, gpm2: gpio-147 ( |usb4640 reset ) out hi GPIOs 148-155, platform/11000000.pinctrl, gpm3: GPIOs 156-163, platform/11000000.pinctrl, gpm4: gpio-156 ( |? ) out lo gpio-157 ( |? ) out hi gpio-158 ( |? ) out hi gpio-159 ( |? ) out hi ......
查看系統interrupt資源使用情況
[root@tiny4412 ]# cat /proc/interrupts CPU0 CPU1 CPU2 CPU3 36: 0 0 0 0 GIC 89 Edge mct_comp_irq 37: 4039 1439 1133 2185 GIC 28 Edge MCT 44: 34 0 0 0 GIC 107 Edge mmc0 45: 1 0 0 0 GIC 103 Edge 12480000.hsotg, 12480000.hsotg, dwc2_hsotg:usb1 46: 266 0 0 0 GIC 102 Edge ehci_hcd:usb2, ohci_hcd:usb3 47: 77 0 0 0 GIC 84 Edge 13800000.serial 51: 1 0 0 0 GIC 67 Edge 12680000.pdma 52: 0 0 0 0 GIC 68 Edge 12690000.pdma 53: 0 0 0 0 GIC 66 Edge 12850000.mdma 65: 0 0 0 0 GIC 79 Edge 11400000.pinctrl 66: 1 0 0 0 GIC 78 Edge 11000000.pinctrl 84: 0 0 0 0 COMBINER 80 Edge 3860000.pinctrl 85: 0 0 0 0 GIC 104 Edge 106e0000.pinctrl 96: 1 0 0 0 exynos_gpio_irq_chip 2 Edge 12530000.sdhci cd IPI0: 0 1 1 1 CPU wakeup interrupts IPI1: 0 0 0 0 Timer broadcast interrupts IPI2: 853 1531 516 580 Rescheduling interrupts IPI3: 0 3 3 3 Function call interrupts IPI4: 0 1 1 1 Single function call interrupts
