Initial commit for releasing dellfan.

.gitignore

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+dellfan

Makefile

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+#!/usr/bin/make -f
+
+all: dellfan
+
+dellfan: dellfan.c
+	$(CC) -o $@ $^
+
+clean:
+	rm -f dellfan

README.md

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+dellfan - user space utility to control the fan speed on Dell Laptops.
+======================================================================
+
+* Allows to set the fan speed of a Dell laptop to 0 (disabled), 1 (medium) and 2 (full speed).
+
+
+Caveats
+-------
+
+* The BIOS of some newer Dell laptops (Latitude E6420/E6520/E6430/E6530/E6440/E6540/...)
+will override the speed you set unless you disable the BIOS control.
+    * I found two methods of disabling the BIOS control:
+        * By default ``DISABLE_BIOS_METHOD1`` will be used.
+        * If you want to try ``DISABLE_BIOS_METHOD2`` edit the source code.
+    * On my laptop (E6420), when you disable the BIOS control over the fan some weird things happen:
+        * The Fn keys stop working.
+        * Suspend to RAM sometimes stops working: The laptop will power itself off instead of suspending.
+* Please, if you find a new method of disabling the BIOS control, let me know it.
+    * There is a function that allows to discover new codes by proving (use with care).

dellfan.c

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+/*
+ * dellfan - user space utility to control the fan speed on Dell Laptops.
+ *
+ * SMM Management code from i8k. See file drivers/char/i8k.c at Linux kernel.
+ *
+ * Copyright (C) 2001  Massimo Dal Zotto <[email protected]>
+ * Copyright (C) 2014  Carlos Alberto Lopez Perez <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/io.h>
+
+/* This is some information about the codes for different functions on the Dell SMBIOS */
+
+/*
+  http://brouille.tuxfamily.org/junk/fan.c
+  cmd     function  (thanks to Andrew Paprocki)
+  0x00a3  get current speed indicator of a fan (args: fan)
+  0x01a3  set speed of a fan (args: fan & speed)
+  0x02a3  get RPM of a fan (args: fan)
+  0x03a3  ??? (1 byte)
+  0x04a3  get nominal fan speed (2 args)
+  0x05a3  get fan tolerance speed (2 args)
+  0x10a3  get sensor temperature (1 arg: sensor#)
+  0x11a3  ???
+  0x12a3  arg 0x0003=NBSVC-Query
+          arg 0x0000=NBSVC-Clear
+          arg 0x122=NBSVC-Start Trend
+          arg 0x0100=NBSVC-Stop Trend
+          arg 0x02??=NBSVC-Read
+  0x21a3  ??? (2 args: 1 byte (oder 0x16) + 1 byte)
+  0x22a3  get charger info (1 arg)
+  0x23a3  ??? (4 args: 2x 1 byte, 1xword, 1xdword)
+  0x24a3  get adaptor info status (1 arg oder 0x03)
+  0x30a3  ??? (no args)
+  0x31a3  ??? (no args)
+  0x32a3  ??? (no args)
+  0x33a3  ??? (no args)
+  0x36a3  get hotkey scancode list (args see diags)
+  0x37a3  ??? (no args)
+  0x40a3  get docking state (no args)
+  0xf0a3  ??? (2 args)
+  0xfea3  check SMBIOS version (1 arg)
+  0xffa3  check SMBIOS interface (returns:"DELLDIAG")
+*/
+
+/* The codes for DISABLE_BIOS_* were obtained experimentally on a E6420 with the
+ * following algorithm:
+ * probing many codes in a loop
+ * putting the speed to maximum, sleeping some seconds, and checking the speed back.
+ * Check the function probecodes()
+ */
+#define DISABLE_BIOS_METHOD1 0x30a3
+#define ENABLE_BIOS_METHOD1  0x31a3
+#define DISABLE_BIOS_METHOD2 0x34a3
+#define ENABLE_BIOS_METHOD2  0x35a3
+#define ENABLE_FN            0x32a3
+#define SET_FAN              0x01a3
+#define GET_FAN              0x00a3
+#define FN_STATUS            0x0025
+
+int init_ioperm(void)
+{
+    if (ioperm(0xb2, 4, 1))
+        perror("ioperm:");
+    if (ioperm(0x84, 4, 1))
+        perror("ioperm:");
+}
+
+struct smm_regs {
+    unsigned int eax;
+    unsigned int ebx __attribute__ ((packed));
+    unsigned int ecx __attribute__ ((packed));
+    unsigned int edx __attribute__ ((packed));
+    unsigned int esi __attribute__ ((packed));
+    unsigned int edi __attribute__ ((packed));
+};
+
+static int i8k_smm(struct smm_regs *regs)
+{
+    int rc;
+    int eax = regs->eax;
+
+
+    asm volatile("pushq %%rax\n\t"
+            "movl 0(%%rax),%%edx\n\t"
+            "pushq %%rdx\n\t"
+            "movl 4(%%rax),%%ebx\n\t"
+            "movl 8(%%rax),%%ecx\n\t"
+            "movl 12(%%rax),%%edx\n\t"
+            "movl 16(%%rax),%%esi\n\t"
+            "movl 20(%%rax),%%edi\n\t"
+            "popq %%rax\n\t"
+            "out %%al,$0xb2\n\t"
+            "out %%al,$0x84\n\t"
+            "xchgq %%rax,(%%rsp)\n\t"
+            "movl %%ebx,4(%%rax)\n\t"
+            "movl %%ecx,8(%%rax)\n\t"
+            "movl %%edx,12(%%rax)\n\t"
+            "movl %%esi,16(%%rax)\n\t"
+            "movl %%edi,20(%%rax)\n\t"
+            "popq %%rdx\n\t"
+            "movl %%edx,0(%%rax)\n\t"
+            "pushfq\n\t"
+            "popq %%rax\n\t"
+            "andl $1,%%eax\n"
+            :"=a"(rc)
+            :    "a"(regs)
+            :    "%ebx", "%ecx", "%edx", "%esi", "%edi");
+
+    if (rc != 0 || (regs->eax & 0xffff) == 0xffff || regs->eax == eax)
+            return -1;
+
+    return 0;
+}
+
+
+int send(unsigned int cmd, unsigned int arg) {
+
+    struct smm_regs regs = { .eax = cmd, };
+
+    regs.ebx = arg;
+
+    i8k_smm(&regs);
+    return regs.eax ;
+
+}
+
+/* sets the speed and returns the speed of the fan after that */
+int set_speed(int speed) {
+
+    if ( speed == 0 ) {
+        send(SET_FAN,0x0000);
+    } else if ( speed == 1 ) {
+        send(SET_FAN,0x0100);
+    } else if ( speed == 2 ) {
+        send(SET_FAN,0x0200);
+    } else {
+        printf("Ignoring unknown speed: %d\n",speed);
+    }
+    // return the speed the fan has now
+    return send(GET_FAN,0);
+}
+
+
+int probecodes (void) {
+
+    printf("Please tune the startcode by editing the source code\n");
+    /* Remove the following exit call to enable this routine.
+     *
+     * *WARNING:* Proving for random codes in the SMBIOS management can
+     * cause unexpected behaviour (even crashes or data loss) on your machine.
+     *
+     * USE AT YOUR OWN RISK!!
+     */
+    exit(EXIT_FAILURE);
+
+    /* If you want to test this fast, use startcode=0x30a0 (for example)
+     * and you should see that the code 0x30a3 is detected.
+     * If you want to test all the codes then use startcode=0x0000 but
+     * this will take a while.
+     */
+    int startcode=0x0001;
+    int fanstatus, trycode;
+
+    // Set the speed to 2, sleep 3 seconds and get the speed of the fan
+    set_speed(2);
+    sleep(3);
+    fanstatus = send(GET_FAN,0);
+    if (fanstatus == 2 ) {
+        printf ("Your fan status is already set to full speed.\n"
+                "In order for this to work, please set it to auto (enable BIOS control)\n"
+                "And stop any process that is consuming CPU resources\n");
+        exit(EXIT_FAILURE);
+    }
+
+    for (trycode=startcode; trycode <= 0xFFFF; trycode++) {
+        printf ("Probing code: %#06x\n",trycode);
+        // Send the code
+        send(trycode,0);
+        // Set the speed to 2, sleep 3 seconds and get the speed of the fan
+        set_speed(2);
+        sleep(3);
+        fanstatus = send(GET_FAN,0);
+        // If the fan is still 2 this is because the previous code disabled
+        // the BIOS control of the fan.
+        // Please ensure that your system is idle when running this (otherwise
+        // the BIOS could set the fan to max speed to cool down your system
+        // because of the load)
+        if (fanstatus == 2 ) {
+            printf ("The code %#06x disabled the FAN control!!!\n",trycode);
+            printf ("Enabling BIOS control back...\n");
+            send(ENABLE_BIOS_METHOD1,0);
+            sleep(3);
+            fanstatus = send(GET_FAN,0);
+            if (fanstatus == 2 ) {
+                printf ("ERROR: Unable to bring BIOS control back.\n");
+                exit (EXIT_FAILURE);
+            }
+        }
+    }
+}
+
+
+int main(int argc, char **argv) {
+
+    int speed, disable;
+    unsigned int tries;
+    unsigned int xarg;
+
+    if (geteuid() != 0) {
+        printf("need root privileges\n");
+        exit(EXIT_FAILURE);
+    }
+
+    if (argc < 2) {
+        printf ("Use: %s speed [disable]\n",argv[0]);
+        printf ("\tspeed = {0,1,2}\n");
+        printf ("\t\t\t[Use speed=9 to probe for SMBIOS codes to disable the BIOS fan control.]\n");
+        printf ("\tdisable = {0,1}\n");
+        exit(EXIT_FAILURE);
+    }
+
+    speed = atoi(argv[1]);
+    init_ioperm();
+
+    if (speed == 9)
+        return probecodes();
+
+    if (argc > 2) {
+        disable = atoi(argv[2]);
+        if (disable == 1) {
+            send(DISABLE_BIOS_METHOD1,0);
+            printf ("BIOS CONTROL DISABLED\n");
+        }
+        else if (disable == 0) {
+            send(ENABLE_BIOS_METHOD1,0);
+            printf ("BIOS CONTROL ENABLED\n");
+        }
+        else  {
+            printf ("Use 0 to enable bios control or 1 to disable it\n");
+            exit(EXIT_FAILURE);
+        }
+    }
+
+    printf ("Setting speed to: %d\n", speed );
+    printf ("Speed is now at: %d\n", set_speed(speed));
+
+}