[media] lirc_serial: use precision ktime rather than guessing
This makes transmission more reliable and the code much cleaner. Signed-off-by: Sean Young <sean@mess.org> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Sean Young
Mauro Carvalho Chehab
parent
b66db53f8d
commit
0a84763484
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@ -21,29 +21,6 @@
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* GNU General Public License for more details.
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*/
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/*
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* Steve's changes to improve transmission fidelity:
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* - for systems with the rdtsc instruction and the clock counter, a
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* send_pule that times the pulses directly using the counter.
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* This means that the IR_SERIAL_TRANSMITTER_LATENCY fudge is
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* not needed. Measurement shows very stable waveform, even where
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* PCI activity slows the access to the UART, which trips up other
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* versions.
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* - For other system, non-integer-microsecond pulse/space lengths,
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* done using fixed point binary. So, much more accurate carrier
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* frequency.
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* - fine tuned transmitter latency, taking advantage of fractional
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* microseconds in previous change
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* - Fixed bug in the way transmitter latency was accounted for by
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* tuning the pulse lengths down - the send_pulse routine ignored
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* this overhead as it timed the overall pulse length - so the
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* pulse frequency was right but overall pulse length was too
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* long. Fixed by accounting for latency on each pulse/space
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* iteration.
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*
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* Steve Davies <steve@daviesfam.org> July 2001
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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@ -64,8 +41,8 @@ struct serial_ir_hw {
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u8 off;
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unsigned set_send_carrier:1;
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unsigned set_duty_cycle:1;
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long (*send_pulse)(unsigned long length);
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void (*send_space)(long length);
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void (*send_pulse)(unsigned int length, ktime_t edge);
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void (*send_space)(void);
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spinlock_t lock;
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};
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@ -87,11 +64,11 @@ static int sense = -1; /* -1 = auto, 0 = active high, 1 = active low */
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static bool txsense; /* 0 = active high, 1 = active low */
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/* forward declarations */
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static long send_pulse_irdeo(unsigned long length);
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static void send_space_irdeo(long length);
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static void send_pulse_irdeo(unsigned int length, ktime_t edge);
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static void send_space_irdeo(void);
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#ifdef CONFIG_IR_SERIAL_TRANSMITTER
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static long send_pulse_homebrew(unsigned long length);
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static void send_space_homebrew(long length);
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static void send_pulse_homebrew(unsigned int length, ktime_t edge);
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static void send_space_homebrew(void);
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#endif
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static struct serial_ir_hw hardware[] = {
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@ -137,8 +114,6 @@ static struct serial_ir_hw hardware[] = {
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.signal_pin_change = UART_MSR_DDCD,
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.on = 0,
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.off = (UART_MCR_RTS | UART_MCR_DTR | UART_MCR_OUT2),
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.send_pulse = NULL,
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.send_space = NULL,
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},
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[IR_IGOR] = {
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@ -166,51 +141,11 @@ struct serial_ir {
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unsigned int freq;
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unsigned int duty_cycle;
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unsigned long period;
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unsigned long pulse_width, space_width;
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unsigned int pulse_width, space_width;
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};
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static struct serial_ir serial_ir;
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#if defined(__i386__)
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/*
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* From:
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* Linux I/O port programming mini-HOWTO
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* Author: Riku Saikkonen <Riku.Saikkonen@hut.fi>
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* v, 28 December 1997
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*
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* [...]
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* Actually, a port I/O instruction on most ports in the 0-0x3ff range
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* takes almost exactly 1 microsecond, so if you're, for example, using
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* the parallel port directly, just do additional inb()s from that port
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* to delay.
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* [...]
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*/
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/* transmitter latency 1.5625us 0x1.90 - this figure arrived at from
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* comment above plus trimming to match actual measured frequency.
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* This will be sensitive to cpu speed, though hopefully most of the 1.5us
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* is spent in the uart access. Still - for reference test machine was a
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* 1.13GHz Athlon system - Steve
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*/
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/*
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* changed from 400 to 450 as this works better on slower machines;
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* faster machines will use the rdtsc code anyway
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*/
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#define IR_SERIAL_TRANSMITTER_LATENCY 450
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#else
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/* does anybody have information on other platforms ? */
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/* 256 = 1<<8 */
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#define IR_SERIAL_TRANSMITTER_LATENCY 256
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#endif /* __i386__ */
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/*
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* FIXME: should we be using hrtimers instead of this
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* IR_SERIAL_TRANSMITTER_LATENCY nonsense?
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*/
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/* fetch serial input packet (1 byte) from register offset */
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static u8 sinp(int offset)
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{
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@ -247,96 +182,21 @@ static void off(void)
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soutp(UART_MCR, hardware[type].off);
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}
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#ifndef MAX_UDELAY_MS
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#define MAX_UDELAY_US 5000
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#else
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#define MAX_UDELAY_US (MAX_UDELAY_MS*1000)
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#endif
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static void safe_udelay(unsigned long usecs)
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{
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while (usecs > MAX_UDELAY_US) {
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udelay(MAX_UDELAY_US);
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usecs -= MAX_UDELAY_US;
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}
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udelay(usecs);
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}
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#ifdef USE_RDTSC
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/*
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* This is an overflow/precision juggle, complicated in that we can't
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* do long long divide in the kernel
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*/
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/*
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* When we use the rdtsc instruction to measure clocks, we keep the
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* pulse and space widths as clock cycles. As this is CPU speed
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* dependent, the widths must be calculated in init_port and ioctl
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* time
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*/
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static int init_timing_params(unsigned int new_duty_cycle,
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static void init_timing_params(unsigned int new_duty_cycle,
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unsigned int new_freq)
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{
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__u64 loops_per_sec, work;
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serial_ir.duty_cycle = new_duty_cycle;
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serial_ir.freq = new_freq;
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loops_per_sec = __this_cpu_read(cpu.info.loops_per_jiffy);
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loops_per_sec *= HZ;
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/* How many clocks in a microsecond?, avoiding long long divide */
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work = loops_per_sec;
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work *= 4295; /* 4295 = 2^32 / 1e6 */
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/*
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* Carrier period in clocks, approach good up to 32GHz clock,
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* gets carrier frequency within 8Hz
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*/
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serial_ir.period = loops_per_sec >> 3;
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serial_ir.pperiod /= (freq >> 3);
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/* Derive pulse and space from the period */
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serial_ir.ppulse_width = serial_ir.period * serial.ir.duty_cycle / 100;
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serial_ir.pspace_width = serial_ir.period - serial_ir.pulse_width;
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pr_debug("in init_timing_params, freq=%d, duty_cycle=%d, clk/jiffy=%ld, pulse=%ld, space=%ld, conv_us_to_clocks=%ld\n",
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freq, duty_cycle, __this_cpu_read(cpu_info.loops_per_jiffy),
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pulse_width, space_width, conv_us_to_clocks);
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return 0;
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serial_ir.pulse_width = DIV_ROUND_CLOSEST(
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new_duty_cycle * NSEC_PER_SEC, new_freq * 100l);
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serial_ir.space_width = DIV_ROUND_CLOSEST(
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(100l - new_duty_cycle) * NSEC_PER_SEC, new_freq * 100l);
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}
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#else /* ! USE_RDTSC */
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static int init_timing_params(unsigned int new_duty_cycle,
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unsigned int new_freq)
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static void send_pulse_irdeo(unsigned int length, ktime_t target)
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{
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/*
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* period, pulse/space width are kept with 8 binary places -
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* IE multiplied by 256.
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*/
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if (256 * 1000000L / new_freq * new_duty_cycle / 100 <=
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IR_SERIAL_TRANSMITTER_LATENCY)
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return -EINVAL;
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if (256 * 1000000L / new_freq * (100 - new_duty_cycle) / 100 <=
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IR_SERIAL_TRANSMITTER_LATENCY)
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return -EINVAL;
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serial_ir.duty_cycle = new_duty_cycle;
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serial_ir.freq = new_freq;
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serial_ir.period = 256 * 1000000L / serial_ir.freq;
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serial_ir.pulse_width = serial_ir.period * serial_ir.duty_cycle / 100;
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serial_ir.space_width = serial_ir.period - serial_ir.pulse_width;
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pr_debug("in init_timing_params, freq=%d pulse=%ld, space=%ld\n",
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serial_ir.freq, serial_ir.pulse_width,
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serial_ir.space_width);
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return 0;
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}
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#endif /* USE_RDTSC */
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/* return value: space length delta */
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static long send_pulse_irdeo(unsigned long length)
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{
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long rawbits, ret;
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long rawbits;
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int i;
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unsigned char output;
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unsigned char chunk, shifted;
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@ -365,84 +225,53 @@ static long send_pulse_irdeo(unsigned long length)
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while (!(sinp(UART_LSR) & UART_LSR_TEMT))
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;
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}
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if (i == 0)
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ret = (-rawbits) * 10000 / 1152;
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else
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ret = (3 - i) * 3 * 10000 / 1152 + (-rawbits) * 10000 / 1152;
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return ret;
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}
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/* Version using udelay() */
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/*
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* here we use fixed point arithmetic, with 8
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* fractional bits. that gets us within 0.1% or so of the right average
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* frequency, albeit with some jitter in pulse length - Steve
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*
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* This should use ndelay instead.
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*/
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/* To match 8 fractional bits used for pulse/space length */
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static void send_space_irdeo(long length)
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static void send_space_irdeo(void)
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{
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if (length <= 0)
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return;
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safe_udelay(length);
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}
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#ifdef CONFIG_IR_SERIAL_TRANSMITTER
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static long send_pulse_homebrew_softcarrier(unsigned long length)
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static void send_pulse_homebrew_softcarrier(unsigned int length, ktime_t edge)
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{
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int flag;
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unsigned long actual, target, d;
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length <<= 8;
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actual = 0; target = 0; flag = 0;
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while (actual < length) {
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if (flag) {
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off();
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target += serial_ir.space_width;
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} else {
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on();
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target += serial_ir.pulse_width;
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}
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d = (target - actual -
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IR_SERIAL_TRANSMITTER_LATENCY + 128) >> 8;
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ktime_t now, target = ktime_add_us(edge, length);
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/*
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* Note - we've checked in ioctl that the pulse/space
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* widths are big enough so that d is > 0
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* delta should never exceed 4 seconds and on m68k
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* ndelay(s64) does not compile; so use s32 rather than s64.
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*/
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udelay(d);
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actual += (d << 8) + IR_SERIAL_TRANSMITTER_LATENCY;
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flag = !flag;
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}
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return (actual-length) >> 8;
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}
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static long send_pulse_homebrew(unsigned long length)
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{
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if (length <= 0)
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return 0;
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if (softcarrier)
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return send_pulse_homebrew_softcarrier(length);
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s32 delta;
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for (;;) {
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now = ktime_get();
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if (ktime_compare(now, target) >= 0)
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break;
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on();
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safe_udelay(length);
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return 0;
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edge = ktime_add_ns(edge, serial_ir.pulse_width);
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delta = ktime_to_ns(ktime_sub(edge, now));
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if (delta > 0)
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ndelay(delta);
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now = ktime_get();
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off();
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if (ktime_compare(now, target) >= 0)
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break;
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edge = ktime_add_ns(edge, serial_ir.space_width);
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delta = ktime_to_ns(ktime_sub(edge, now));
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if (delta > 0)
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ndelay(delta);
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}
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}
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static void send_space_homebrew(long length)
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static void send_pulse_homebrew(unsigned int length, ktime_t edge)
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{
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if (softcarrier)
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send_pulse_homebrew_softcarrier(length, edge);
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else
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on();
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}
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static void send_space_homebrew(void)
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{
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off();
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if (length <= 0)
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return;
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safe_udelay(length);
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}
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#endif
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@ -746,7 +575,8 @@ static int serial_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
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unsigned int count)
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{
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unsigned long flags;
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long delta = 0;
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ktime_t edge;
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s64 delta;
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int i;
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spin_lock_irqsave(&hardware[type].lock, flags);
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@ -754,11 +584,23 @@ static int serial_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
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/* DTR, RTS down */
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on();
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}
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edge = ktime_get();
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for (i = 0; i < count; i++) {
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if (i%2)
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hardware[type].send_space(txbuf[i] - delta);
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hardware[type].send_space();
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else
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delta = hardware[type].send_pulse(txbuf[i]);
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hardware[type].send_pulse(txbuf[i], edge);
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edge = ktime_add_us(edge, txbuf[i]);
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delta = ktime_us_delta(edge, ktime_get());
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if (delta > 25) {
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spin_unlock_irqrestore(&hardware[type].lock, flags);
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usleep_range(delta - 25, delta + 25);
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spin_lock_irqsave(&hardware[type].lock, flags);
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}
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else if (delta > 0)
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udelay(delta);
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}
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off();
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spin_unlock_irqrestore(&hardware[type].lock, flags);
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@ -767,7 +609,8 @@ static int serial_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
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static int serial_ir_tx_duty_cycle(struct rc_dev *dev, u32 cycle)
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{
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return init_timing_params(cycle, serial_ir.freq);
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init_timing_params(cycle, serial_ir.freq);
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return 0;
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}
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static int serial_ir_tx_carrier(struct rc_dev *dev, u32 carrier)
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@ -775,7 +618,8 @@ static int serial_ir_tx_carrier(struct rc_dev *dev, u32 carrier)
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if (carrier > 500000 || carrier < 20000)
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return -EINVAL;
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return init_timing_params(serial_ir.duty_cycle, carrier);
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init_timing_params(serial_ir.duty_cycle, carrier);
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return 0;
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}
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static int serial_ir_suspend(struct platform_device *dev,
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