TASK08: IRQ handling

04_basic_struct/README.md

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+## Basic structure homework
+Implement object with name “MyObject” which is parent of kernel_kobj.    
+Object should include linked_list structure.    
+This object should contain sysfs attribute with name “list”.    
+On read form attribute “list” it should show content of the objects linked list.    
+On write to attribute “list” it should add new string to the objects linked list.    
+!! Do not forget properly free all the resources during rmmod.    

05_timers/README.md

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+## Homework: Linux Kernel Time Management
+
+1. Implement program which return absolute time in user space.
+Use clock_gettime() from time.h. Try different clock id.
+Find the difference. Show possible clock resolution provided by clock_getres().
+
+2. Implement kernel module with API in sysfs, which returns relative
+time in maximum possible resolution passed since previous read of it.
+Implement kernel module with API in sysfs which returns absolute time
+of previous reading with maximum resolution like ‘400.123567’ seconds.

06_memory/README.md

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+# Memory management
+
+## Homework
+1. Create user-space C or C++ program which tries to allocate buffers
+  with sizes 2^x for x in range from 0 to maximium possible value 
+  using functions:
+  **malloc, calloc, alloca, (optional for C++) new **.
+  Measure time of each allocation/freeing.
+  2^x means x power of 2 in this task.
+Pull request should contains program source code and program output
+in text format.
+
+2. Create kernel module and test allocation/freeing time for functions:
+  **kmalloc, kzmalloc, vmalloc, get_free_pages,
+   (optional and only for drivers integrated to kernel)alloc_bootmem**.
+  Measure the time of each allocation/freeing except alloc_bootmem.
+  The results should be presented in text file table with followed columns:
+  Buffer size, allocation time, freeing time.
+  Size unit is 1 byte, time unit is 1 ns.
+
+Pull request should contains source code of developed driver, Makefile
+and program output from system log in text format.

07_procfs/README.md

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+## Lesson 07 - ProcFS interface and orange pi bootup
+
+* Update your existing sysfs kernel module with procfs API:
+* Create folder in procfs file system;
+* Create entry that returns module author name;
+* Create entry that returns amount of "store" callback calls;
+* Create entry that returns amount of "show" callback calls.
+* Build image for orange pi zero
+* Attach console output from your development board
+

08_irq_handling/Makefile

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+KERNELDIR ?= ../../output/build/linux-5.10.10/ #WARNING relative path
+
+TARGET = led_mod_irq
+
+obj-m := $(TARGET).o
+CFLAGS_$(TARGET).o := -std=gnu11 -DDEBUG -Wno-declaration-after-statement
+
+all:
+	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
+
+clean:
+	$(MAKE) -C $(KERNELDIR) M=$(PWD) clean

08_irq_handling/README.md

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+## Lesson 08 - IRQ handling
+
+Run polling example on your board.
+Modify you driver to enable irq handling instead of polling mechanism
+

08_irq_handling/irq_list.txt

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+# cat /proc/interrupts 
+           CPU0       CPU1       CPU2       CPU3       
+ 25:          0          0          0          0     GICv2  50 Level     timer@1c20c00
+ 26:          0          0          0          0     GICv2  29 Level     arch_timer
+ 27:      59053       9053       4143       4952     GICv2  30 Level     arch_timer
+ 30:          0          0          0          0     GICv2  82 Level     1c02000.dma-controller
+ 32:       9407          0          0          0     GICv2  92 Level     sunxi-mmc
+ 33:      37027          0          0          0     GICv2  93 Level     sunxi-mmc
+ 34:          0          0          0          0     GICv2  81 Level     1c17000.mailbox
+ 35:          0          0          0          0     GICv2 103 Level     musb-hdrc.2.auto
+ 36:          0          0          0          0     GICv2 104 Level     ehci_hcd:usb1
+ 37:          0          0          0          0     GICv2 105 Level     ohci_hcd:usb2
+ 38:          0          0          0          0     GICv2 106 Level     ehci_hcd:usb3
+ 39:          0          0          0          0     GICv2 107 Level     ohci_hcd:usb4
+ 43:          0          0          0          0     GICv2 114 Level     eth0
+ 44:          2          0          0          0     GICv2  97 Level     sun6i-spi
+ 45:          0          0          0          0     GICv2  98 Level     sun6i-spi
+ 47:       1199          0          0          0     GICv2  32 Level     ttyS0
+ 48:          0          0          0          0     GICv2  72 Level     1f00000.rtc
+ 51:          0          0          0          0     GICv2 125 Level     1400000.deinterlace
+ 52:          0          0          0          0     GICv2  90 Level     1c0e000.video-codec
+ 53:          0          0          0          0     GICv2 126 Level     sun8i-ce-ns
+ 54:          0          0          0          0     GICv2 129 Level     gp
+ 55:          0          0          0          0     GICv2 130 Level     gpmmu
+ 56:          0          0          0          0     GICv2 131 Level     pp0
+ 57:          0          0          0          0     GICv2 132 Level     ppmmu0
+ 58:          0          0          0          0     GICv2 134 Level     pp1
+ 59:          0          0          0          0     GICv2 135 Level     ppmmu1
+ 61:       5134          0          0          0     GICv2  63 Level     ths
+ 62:          0          0          0          0     GICv2 152 Level     arm-pmu
+ 63:          0          0          0          0     GICv2 153 Level     arm-pmu
+ 64:          0          0          0          0     GICv2 154 Level     arm-pmu
+ 65:          0          0          0          0     GICv2 155 Level     arm-pmu
+105:         34          0          0          0  sunxi_pio_edge  39 Edge      my_button_irq
+108:        383          0          0          0  sunxi_pio_edge  42 Edge      xradio
+110:          1          0          0          0  sunxi_pio_edge  44 Edge      usb0-id-det
+IPI0:          0          0          0          0  CPU wakeup interrupts
+IPI1:          0          0          0          0  Timer broadcast interrupts
+IPI2:         45         47         69         98  Rescheduling interrupts
+IPI3:        942       6812       4574       4547  Function call interrupts
+IPI4:          0          0          0          0  CPU stop interrupts
+IPI5:      25233       3185       1603       3654  IRQ work interrupts
+IPI6:          0          0          0          0  completion interrupts
+Err:          0
+

08_irq_handling/led_mod.c

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+#define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__
+
+#include <linux/module.h>
+#include <linux/gpio.h>
+#include <linux/ktime.h>
+#include <linux/interrupt.h>
+
+#define GPIO_NUMBER(port, bit) (32 * (port) + (bit))
+
+/*	https://linux-sunxi.org/Xunlong_Orange_Pi_PC#LEDs
+ *  Board config for OPI-PC:
+ *	LED GREEN (PL10): GPIO_11_10
+ *	LED RED   (PA15): GPIO_0_15  
+ *	BUTTON    (PG7) : GPIO_6_7
+ *
+ *  https://linux-sunxi.org/Xunlong_Orange_Pi_Zero#LEDs
+ *  Board config for OPI-Zero:
+ *	LED GREEN (PL10): GPIO_11_10 
+ *	LED RED   (PA17): GPIO_0_17 
+ *	BUTTON    (PG7) : GPIO_6_7
+ *  
+ */
+
+#define LED_GREEN GPIO_NUMBER(11, 10)
+#define LED_RED GPIO_NUMBER(0, 17)
+#define BUTTON GPIO_NUMBER(6, 7)
+
+#define TIMER_ENABLE 1
+
+static int ledg_gpio = -1;
+static int ledr_gpio = -1;
+static int button_gpio = -1;
+static int button_state = -1;
+static int button_cnt = -1;
+
+#ifdef TIMER_ENABLE
+static ktime_t timer_period;
+struct hrtimer button_timer;
+
+static enum hrtimer_restart timer_callback(struct hrtimer *timer)
+{
+	int cur_button_state;
+
+	cur_button_state = gpio_get_value(button_gpio);
+	button_cnt = (cur_button_state == button_state) ? (button_cnt + 1) : 0;
+	button_state = cur_button_state;
+	gpio_set_value(ledr_gpio, ((button_cnt == 20) ? 1 : 0));
+	if (button_cnt >= 20)
+		gpio_set_value(ledg_gpio, !button_state);
+	hrtimer_forward(timer, timer->base->get_time(), timer_period);
+	return HRTIMER_RESTART;  //restart timer
+}
+#endif
+
+static int led_gpio_init(int gpio, int *led_gpio)
+{
+	int res;
+
+	res = gpio_direction_output(gpio, 0);
+	if (res != 0)
+		return res;
+
+	*led_gpio = gpio;
+	return 0;
+}
+
+static int button_gpio_init(int gpio)
+{
+	int res;
+
+	res = gpio_request(gpio, "Onboard user button");
+	if (res != 0)
+		return res;
+
+	res = gpio_direction_input(gpio);
+	if (res != 0)
+		goto err_input;
+
+	button_gpio = gpio;
+	pr_info("Init GPIO%d OK\n", button_gpio);
+	button_state = gpio_get_value(button_gpio);
+	button_cnt = 0;
+
+	return 0;
+
+err_input:
+	gpio_free(gpio);
+	return res;
+}
+
+static void button_gpio_deinit(void)
+{
+	if (button_gpio >= 0) {
+		gpio_free(button_gpio);
+		pr_info("Deinit GPIO%d\n", button_gpio);
+	}
+}
+
+/* Module entry/exit points */
+static int __init led_mod_init(void)
+{
+	int res;
+	pr_info("GPIO Init\n");
+
+	res = button_gpio_init(BUTTON);
+	if (res != 0) {
+		pr_err("Can't set GPIO%d for button\n", BUTTON);
+		return res;
+	}
+#ifdef TIMER_ENABLE
+	timer_period = ktime_set(0, 1000000);      /*1 msec*/
+	hrtimer_init(&button_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	hrtimer_start(&button_timer, timer_period, HRTIMER_MODE_REL);
+	button_timer.function = timer_callback;
+#endif
+	res = led_gpio_init(LED_GREEN, &ledg_gpio);
+	if (res != 0) {
+		pr_err("Can't set GPIO%d for output\n", LED_GREEN);
+		goto err_led;
+	}
+
+	gpio_set_value(ledg_gpio, 0);
+
+	res = led_gpio_init(LED_RED, &ledr_gpio);
+	if (res != 0) {
+		pr_err("Can't set GPIO%d for output\n", LED_RED);
+		goto err_led;
+	}
+	gpio_set_value(ledr_gpio, 1);
+
+	return 0;
+
+err_led:
+	button_gpio_deinit();
+	return res;
+}
+
+static void __exit led_mod_exit(void)
+{
+	gpio_set_value(ledg_gpio, 0);
+	gpio_set_value(ledr_gpio, 0);
+	button_gpio_deinit();
+#ifdef TIMER_ENABLE
+	hrtimer_cancel(&button_timer);
+#endif
+}
+
+module_init(led_mod_init);
+module_exit(led_mod_exit);
+
+MODULE_AUTHOR("Oleksandr Posukhov [email protected]>");
+MODULE_DESCRIPTION("LED Test");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("0.1");