From 0a847634849c64f6f477c68fb0e4baa24b09abd1 Mon Sep 17 00:00:00 2001 From: Sean Young Date: Mon, 21 Nov 2016 19:55:52 -0200 Subject: [PATCH] [media] lirc_serial: use precision ktime rather than guessing This makes transmission more reliable and the code much cleaner. Signed-off-by: Sean Young Signed-off-by: Mauro Carvalho Chehab --- drivers/staging/media/lirc/lirc_serial.c | 286 ++++++----------------- 1 file changed, 65 insertions(+), 221 deletions(-) diff --git a/drivers/staging/media/lirc/lirc_serial.c b/drivers/staging/media/lirc/lirc_serial.c index 05a8a47aecef..7d1c2afcfdb5 100644 --- a/drivers/staging/media/lirc/lirc_serial.c +++ b/drivers/staging/media/lirc/lirc_serial.c @@ -21,29 +21,6 @@ * GNU General Public License for more details. */ -/* - * Steve's changes to improve transmission fidelity: - * - for systems with the rdtsc instruction and the clock counter, a - * send_pule that times the pulses directly using the counter. - * This means that the IR_SERIAL_TRANSMITTER_LATENCY fudge is - * not needed. Measurement shows very stable waveform, even where - * PCI activity slows the access to the UART, which trips up other - * versions. - * - For other system, non-integer-microsecond pulse/space lengths, - * done using fixed point binary. So, much more accurate carrier - * frequency. - * - fine tuned transmitter latency, taking advantage of fractional - * microseconds in previous change - * - Fixed bug in the way transmitter latency was accounted for by - * tuning the pulse lengths down - the send_pulse routine ignored - * this overhead as it timed the overall pulse length - so the - * pulse frequency was right but overall pulse length was too - * long. Fixed by accounting for latency on each pulse/space - * iteration. - * - * Steve Davies July 2001 - */ - #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include @@ -64,8 +41,8 @@ struct serial_ir_hw { u8 off; unsigned set_send_carrier:1; unsigned set_duty_cycle:1; - long (*send_pulse)(unsigned long length); - void (*send_space)(long length); + void (*send_pulse)(unsigned int length, ktime_t edge); + void (*send_space)(void); spinlock_t lock; }; @@ -87,11 +64,11 @@ static int sense = -1; /* -1 = auto, 0 = active high, 1 = active low */ static bool txsense; /* 0 = active high, 1 = active low */ /* forward declarations */ -static long send_pulse_irdeo(unsigned long length); -static void send_space_irdeo(long length); +static void send_pulse_irdeo(unsigned int length, ktime_t edge); +static void send_space_irdeo(void); #ifdef CONFIG_IR_SERIAL_TRANSMITTER -static long send_pulse_homebrew(unsigned long length); -static void send_space_homebrew(long length); +static void send_pulse_homebrew(unsigned int length, ktime_t edge); +static void send_space_homebrew(void); #endif static struct serial_ir_hw hardware[] = { @@ -137,8 +114,6 @@ static struct serial_ir_hw hardware[] = { .signal_pin_change = UART_MSR_DDCD, .on = 0, .off = (UART_MCR_RTS | UART_MCR_DTR | UART_MCR_OUT2), - .send_pulse = NULL, - .send_space = NULL, }, [IR_IGOR] = { @@ -166,51 +141,11 @@ struct serial_ir { unsigned int freq; unsigned int duty_cycle; - unsigned long period; - unsigned long pulse_width, space_width; + unsigned int pulse_width, space_width; }; static struct serial_ir serial_ir; -#if defined(__i386__) -/* - * From: - * Linux I/O port programming mini-HOWTO - * Author: Riku Saikkonen - * v, 28 December 1997 - * - * [...] - * Actually, a port I/O instruction on most ports in the 0-0x3ff range - * takes almost exactly 1 microsecond, so if you're, for example, using - * the parallel port directly, just do additional inb()s from that port - * to delay. - * [...] - */ -/* transmitter latency 1.5625us 0x1.90 - this figure arrived at from - * comment above plus trimming to match actual measured frequency. - * This will be sensitive to cpu speed, though hopefully most of the 1.5us - * is spent in the uart access. Still - for reference test machine was a - * 1.13GHz Athlon system - Steve - */ - -/* - * changed from 400 to 450 as this works better on slower machines; - * faster machines will use the rdtsc code anyway - */ -#define IR_SERIAL_TRANSMITTER_LATENCY 450 - -#else - -/* does anybody have information on other platforms ? */ -/* 256 = 1<<8 */ -#define IR_SERIAL_TRANSMITTER_LATENCY 256 - -#endif /* __i386__ */ -/* - * FIXME: should we be using hrtimers instead of this - * IR_SERIAL_TRANSMITTER_LATENCY nonsense? - */ - /* fetch serial input packet (1 byte) from register offset */ static u8 sinp(int offset) { @@ -247,96 +182,21 @@ static void off(void) soutp(UART_MCR, hardware[type].off); } -#ifndef MAX_UDELAY_MS -#define MAX_UDELAY_US 5000 -#else -#define MAX_UDELAY_US (MAX_UDELAY_MS*1000) -#endif - -static void safe_udelay(unsigned long usecs) +static void init_timing_params(unsigned int new_duty_cycle, + unsigned int new_freq) { - while (usecs > MAX_UDELAY_US) { - udelay(MAX_UDELAY_US); - usecs -= MAX_UDELAY_US; - } - udelay(usecs); -} - -#ifdef USE_RDTSC -/* - * This is an overflow/precision juggle, complicated in that we can't - * do long long divide in the kernel - */ - -/* - * When we use the rdtsc instruction to measure clocks, we keep the - * pulse and space widths as clock cycles. As this is CPU speed - * dependent, the widths must be calculated in init_port and ioctl - * time - */ - -static int init_timing_params(unsigned int new_duty_cycle, - unsigned int new_freq) -{ - __u64 loops_per_sec, work; - serial_ir.duty_cycle = new_duty_cycle; serial_ir.freq = new_freq; - loops_per_sec = __this_cpu_read(cpu.info.loops_per_jiffy); - loops_per_sec *= HZ; - - /* How many clocks in a microsecond?, avoiding long long divide */ - work = loops_per_sec; - work *= 4295; /* 4295 = 2^32 / 1e6 */ - - /* - * Carrier period in clocks, approach good up to 32GHz clock, - * gets carrier frequency within 8Hz - */ - serial_ir.period = loops_per_sec >> 3; - serial_ir.pperiod /= (freq >> 3); - - /* Derive pulse and space from the period */ - serial_ir.ppulse_width = serial_ir.period * serial.ir.duty_cycle / 100; - serial_ir.pspace_width = serial_ir.period - serial_ir.pulse_width; - pr_debug("in init_timing_params, freq=%d, duty_cycle=%d, clk/jiffy=%ld, pulse=%ld, space=%ld, conv_us_to_clocks=%ld\n", - freq, duty_cycle, __this_cpu_read(cpu_info.loops_per_jiffy), - pulse_width, space_width, conv_us_to_clocks); - return 0; -} -#else /* ! USE_RDTSC */ -static int init_timing_params(unsigned int new_duty_cycle, - unsigned int new_freq) -{ -/* - * period, pulse/space width are kept with 8 binary places - - * IE multiplied by 256. - */ - if (256 * 1000000L / new_freq * new_duty_cycle / 100 <= - IR_SERIAL_TRANSMITTER_LATENCY) - return -EINVAL; - if (256 * 1000000L / new_freq * (100 - new_duty_cycle) / 100 <= - IR_SERIAL_TRANSMITTER_LATENCY) - return -EINVAL; - serial_ir.duty_cycle = new_duty_cycle; - serial_ir.freq = new_freq; - serial_ir.period = 256 * 1000000L / serial_ir.freq; - serial_ir.pulse_width = serial_ir.period * serial_ir.duty_cycle / 100; - serial_ir.space_width = serial_ir.period - serial_ir.pulse_width; - pr_debug("in init_timing_params, freq=%d pulse=%ld, space=%ld\n", - serial_ir.freq, serial_ir.pulse_width, - serial_ir.space_width); - return 0; + serial_ir.pulse_width = DIV_ROUND_CLOSEST( + new_duty_cycle * NSEC_PER_SEC, new_freq * 100l); + serial_ir.space_width = DIV_ROUND_CLOSEST( + (100l - new_duty_cycle) * NSEC_PER_SEC, new_freq * 100l); } -#endif /* USE_RDTSC */ - -/* return value: space length delta */ - -static long send_pulse_irdeo(unsigned long length) +static void send_pulse_irdeo(unsigned int length, ktime_t target) { - long rawbits, ret; + long rawbits; int i; unsigned char output; unsigned char chunk, shifted; @@ -365,84 +225,53 @@ static long send_pulse_irdeo(unsigned long length) while (!(sinp(UART_LSR) & UART_LSR_TEMT)) ; } - - if (i == 0) - ret = (-rawbits) * 10000 / 1152; - else - ret = (3 - i) * 3 * 10000 / 1152 + (-rawbits) * 10000 / 1152; - - return ret; } -/* Version using udelay() */ - -/* - * here we use fixed point arithmetic, with 8 - * fractional bits. that gets us within 0.1% or so of the right average - * frequency, albeit with some jitter in pulse length - Steve - * - * This should use ndelay instead. - */ - -/* To match 8 fractional bits used for pulse/space length */ - -static void send_space_irdeo(long length) +static void send_space_irdeo(void) { - if (length <= 0) - return; - - safe_udelay(length); } #ifdef CONFIG_IR_SERIAL_TRANSMITTER -static long send_pulse_homebrew_softcarrier(unsigned long length) +static void send_pulse_homebrew_softcarrier(unsigned int length, ktime_t edge) { - int flag; - unsigned long actual, target, d; - - length <<= 8; + ktime_t now, target = ktime_add_us(edge, length); + /* + * delta should never exceed 4 seconds and on m68k + * ndelay(s64) does not compile; so use s32 rather than s64. + */ + s32 delta; - actual = 0; target = 0; flag = 0; - while (actual < length) { - if (flag) { - off(); - target += serial_ir.space_width; - } else { - on(); - target += serial_ir.pulse_width; - } - d = (target - actual - - IR_SERIAL_TRANSMITTER_LATENCY + 128) >> 8; - /* - * Note - we've checked in ioctl that the pulse/space - * widths are big enough so that d is > 0 - */ - udelay(d); - actual += (d << 8) + IR_SERIAL_TRANSMITTER_LATENCY; - flag = !flag; + for (;;) { + now = ktime_get(); + if (ktime_compare(now, target) >= 0) + break; + on(); + edge = ktime_add_ns(edge, serial_ir.pulse_width); + delta = ktime_to_ns(ktime_sub(edge, now)); + if (delta > 0) + ndelay(delta); + now = ktime_get(); + off(); + if (ktime_compare(now, target) >= 0) + break; + edge = ktime_add_ns(edge, serial_ir.space_width); + delta = ktime_to_ns(ktime_sub(edge, now)); + if (delta > 0) + ndelay(delta); } - return (actual-length) >> 8; } -static long send_pulse_homebrew(unsigned long length) +static void send_pulse_homebrew(unsigned int length, ktime_t edge) { - if (length <= 0) - return 0; - if (softcarrier) - return send_pulse_homebrew_softcarrier(length); - - on(); - safe_udelay(length); - return 0; + send_pulse_homebrew_softcarrier(length, edge); + else + on(); } -static void send_space_homebrew(long length) +static void send_space_homebrew(void) { off(); - if (length <= 0) - return; - safe_udelay(length); } #endif @@ -746,7 +575,8 @@ static int serial_ir_tx(struct rc_dev *dev, unsigned int *txbuf, unsigned int count) { unsigned long flags; - long delta = 0; + ktime_t edge; + s64 delta; int i; spin_lock_irqsave(&hardware[type].lock, flags); @@ -754,11 +584,23 @@ static int serial_ir_tx(struct rc_dev *dev, unsigned int *txbuf, /* DTR, RTS down */ on(); } + + edge = ktime_get(); for (i = 0; i < count; i++) { if (i%2) - hardware[type].send_space(txbuf[i] - delta); + hardware[type].send_space(); else - delta = hardware[type].send_pulse(txbuf[i]); + hardware[type].send_pulse(txbuf[i], edge); + + edge = ktime_add_us(edge, txbuf[i]); + delta = ktime_us_delta(edge, ktime_get()); + if (delta > 25) { + spin_unlock_irqrestore(&hardware[type].lock, flags); + usleep_range(delta - 25, delta + 25); + spin_lock_irqsave(&hardware[type].lock, flags); + } + else if (delta > 0) + udelay(delta); } off(); spin_unlock_irqrestore(&hardware[type].lock, flags); @@ -767,7 +609,8 @@ static int serial_ir_tx(struct rc_dev *dev, unsigned int *txbuf, static int serial_ir_tx_duty_cycle(struct rc_dev *dev, u32 cycle) { - return init_timing_params(cycle, serial_ir.freq); + init_timing_params(cycle, serial_ir.freq); + return 0; } static int serial_ir_tx_carrier(struct rc_dev *dev, u32 carrier) @@ -775,7 +618,8 @@ static int serial_ir_tx_carrier(struct rc_dev *dev, u32 carrier) if (carrier > 500000 || carrier < 20000) return -EINVAL; - return init_timing_params(serial_ir.duty_cycle, carrier); + init_timing_params(serial_ir.duty_cycle, carrier); + return 0; } static int serial_ir_suspend(struct platform_device *dev, -- 2.20.1