imx: re-work of PWM, add i.MX21 support
* Kconfig enables now HAVE_PWM (this enables in turn the selection of CONFIG_BACKLIGHT_PWM) * changes CONFIG_ARCH_MXyy to CONFIG_MACH_MXyy * fix some register names to match those of the reference manual * write a stub code so that the PWM can be used to program the LCD backlight * convert from #ifdef CONFIG_ARCH_MXxx to cpu_is_mxXX() * remove unneeded defines and fix 80-column "violations" of checkpatch.pl Signed-off-by: Holger Schurig <hs4233@mail.mn-solutions.de> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>hifive-unleashed-5.1
Holger Schurig
Sascha Hauer
parent
6b91edde09
commit
c010dba89b
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@ -48,6 +48,7 @@ config MXC_IRQ_PRIOR
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config MXC_PWM
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tristate "Enable PWM driver"
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depends on ARCH_MXC
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select HAVE_PWM
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help
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Enable support for the i.MX PWM controller(s).
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@ -15,65 +15,26 @@
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#include <linux/clk.h>
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#include <linux/io.h>
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#include <linux/pwm.h>
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#include <mach/hardware.h>
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#if defined CONFIG_ARCH_MX1 || defined CONFIG_ARCH_MX21
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#define PWM_VER_1
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#define PWMCR 0x00 /* PWM Control Register */
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#define PWMSR 0x04 /* PWM Sample Register */
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#define PWMPR 0x08 /* PWM Period Register */
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#define PWMCNR 0x0C /* PWM Counter Register */
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/* i.MX1 and i.MX21 share the same PWM function block: */
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#define PWMCR_HCTR (1 << 18) /* Halfword FIFO Data Swapping */
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#define PWMCR_BCTR (1 << 17) /* Byte FIFO Data Swapping */
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#define PWMCR_SWR (1 << 16) /* Software Reset */
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#define PWMCR_CLKSRC_PERCLK (0 << 15) /* PERCLK Clock Source */
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#define PWMCR_CLKSRC_CLK32 (1 << 15) /* 32KHz Clock Source */
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#define PWMCR_PRESCALER(x) (((x - 1) & 0x7F) << 8) /* PRESCALER */
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#define PWMCR_IRQ (1 << 7) /* Interrupt Request */
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#define PWMCR_IRQEN (1 << 6) /* Interrupt Request Enable */
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#define PWMCR_FIFOAV (1 << 5) /* FIFO Available */
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#define PWMCR_EN (1 << 4) /* Enables/Disables the PWM */
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#define PWMCR_REPEAT(x) (((x) & 0x03) << 2) /* Sample Repeats */
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#define PWMCR_DIV(x) (((x) & 0x03) << 0) /* Clock divider 2/4/8/16 */
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#define MX1_PWMC 0x00 /* PWM Control Register */
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#define MX1_PWMS 0x04 /* PWM Sample Register */
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#define MX1_PWMP 0x08 /* PWM Period Register */
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#define MAX_DIV (128 * 16)
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#endif
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#if defined CONFIG_MACH_MX27 || defined CONFIG_ARCH_MX31
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#define PWM_VER_2
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/* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
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#define PWMCR 0x00 /* PWM Control Register */
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#define PWMSR 0x04 /* PWM Status Register */
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#define PWMIR 0x08 /* PWM Interrupt Register */
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#define PWMSAR 0x0C /* PWM Sample Register */
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#define PWMPR 0x10 /* PWM Period Register */
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#define PWMCNR 0x14 /* PWM Counter Register */
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#define MX3_PWMCR 0x00 /* PWM Control Register */
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#define MX3_PWMSAR 0x0C /* PWM Sample Register */
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#define MX3_PWMPR 0x10 /* PWM Period Register */
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#define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4)
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#define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
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#define MX3_PWMCR_EN (1 << 0)
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#define PWMCR_EN (1 << 0) /* Enables/Disables the PWM */
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#define PWMCR_REPEAT(x) (((x) & 0x03) << 1) /* Sample Repeats */
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#define PWMCR_SWR (1 << 3) /* Software Reset */
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#define PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4)/* PRESCALER */
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#define PWMCR_CLKSRC(x) (((x) & 0x3) << 16)
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#define PWMCR_CLKSRC_OFF (0 << 16)
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#define PWMCR_CLKSRC_IPG (1 << 16)
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#define PWMCR_CLKSRC_IPG_HIGH (2 << 16)
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#define PWMCR_CLKSRC_CLK32 (3 << 16)
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#define PWMCR_POUTC
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#define PWMCR_HCTR (1 << 20) /* Halfword FIFO Data Swapping */
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#define PWMCR_BCTR (1 << 21) /* Byte FIFO Data Swapping */
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#define PWMCR_DBGEN (1 << 22) /* Debug Mode */
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#define PWMCR_WAITEN (1 << 23) /* Wait Mode */
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#define PWMCR_DOZEN (1 << 24) /* Doze Mode */
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#define PWMCR_STOPEN (1 << 25) /* Stop Mode */
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#define PWMCR_FWM(x) (((x) & 0x3) << 26) /* FIFO Water Mark */
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#define MAX_DIV 4096
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#endif
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#define PWMS_SAMPLE(x) ((x) & 0xFFFF) /* Contains a two-sample word */
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#define PWMP_PERIOD(x) ((x) & 0xFFFF) /* Represents the PWM's period */
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#define PWMC_COUNTER(x) ((x) & 0xFFFF) /* Represents the current count value */
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struct pwm_device {
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struct list_head node;
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@ -91,32 +52,52 @@ struct pwm_device {
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int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
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{
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unsigned long long c;
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unsigned long period_cycles, duty_cycles, prescale;
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if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
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return -EINVAL;
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c = clk_get_rate(pwm->clk);
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c = c * period_ns;
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do_div(c, 1000000000);
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period_cycles = c;
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if (cpu_is_mx27() || cpu_is_mx3()) {
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unsigned long long c;
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unsigned long period_cycles, duty_cycles, prescale;
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c = clk_get_rate(pwm->clk);
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c = c * period_ns;
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do_div(c, 1000000000);
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period_cycles = c;
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prescale = period_cycles / 0x10000 + 1;
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prescale = period_cycles / 0x10000 + 1;
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period_cycles /= prescale;
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c = (unsigned long long)period_cycles * duty_ns;
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do_div(c, period_ns);
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duty_cycles = c;
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period_cycles /= prescale;
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c = (unsigned long long)period_cycles * duty_ns;
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do_div(c, period_ns);
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duty_cycles = c;
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#ifdef PWM_VER_2
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writel(duty_cycles, pwm->mmio_base + PWMSAR);
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writel(period_cycles, pwm->mmio_base + PWMPR);
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writel(PWMCR_PRESCALER(prescale - 1) | PWMCR_CLKSRC_IPG_HIGH | PWMCR_EN,
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pwm->mmio_base + PWMCR);
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#elif defined PWM_VER_1
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#error PWM not yet working on MX1 / MX21
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#endif
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writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR);
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writel(period_cycles, pwm->mmio_base + MX3_PWMPR);
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writel(MX3_PWMCR_PRESCALER(prescale - 1) |
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MX3_PWMCR_CLKSRC_IPG_HIGH | MX3_PWMCR_EN,
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pwm->mmio_base + MX3_PWMCR);
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} else if (cpu_is_mx1() || cpu_is_mx21()) {
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/* The PWM subsystem allows for exact frequencies. However,
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* I cannot connect a scope on my device to the PWM line and
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* thus cannot provide the program the PWM controller
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* exactly. Instead, I'm relying on the fact that the
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* Bootloader (u-boot or WinCE+haret) has programmed the PWM
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* function group already. So I'll just modify the PWM sample
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* register to follow the ratio of duty_ns vs. period_ns
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* accordingly.
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*
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* This is good enought for programming the brightness of
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* the LCD backlight.
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*
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* The real implementation would divide PERCLK[0] first by
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* both the prescaler (/1 .. /128) and then by CLKSEL
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* (/2 .. /16).
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*/
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u32 max = readl(pwm->mmio_base + MX1_PWMP);
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u32 p = max * duty_ns / period_ns;
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writel(max - p, pwm->mmio_base + MX1_PWMS);
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} else {
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BUG();
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}
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return 0;
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}
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@ -297,4 +278,3 @@ module_exit(mxc_pwm_exit);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
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