3 files changed, 327 insertions, 0 deletions

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index d298ebdd872d..59124eb4d592 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -372,6 +372,13 @@ config PWM_STI
           To compile this driver as a module, choose M here: the module
           will be called pwm-sti.
 
+config PWM_STMPE
+        bool "STMPE expander PWM export"
+        depends on MFD_STMPE
+        help
+          This enables support for the PWMs found in the STMPE I/O
+          expanders.
+
 config PWM_SUN4I
         tristate "Allwinner PWM support"
         depends on ARCH_SUNXI || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index a196d79fbd3f..98ae3cb4e3e7 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -35,6 +35,7 @@ obj-$(CONFIG_PWM_ROCKCHIP)	+= pwm-rockchip.o
 obj-$(CONFIG_PWM_SAMSUNG)       += pwm-samsung.o
 obj-$(CONFIG_PWM_SPEAR)         += pwm-spear.o
 obj-$(CONFIG_PWM_STI)           += pwm-sti.o
+obj-$(CONFIG_PWM_STMPE)         += pwm-stmpe.o
 obj-$(CONFIG_PWM_SUN4I)         += pwm-sun4i.o
 obj-$(CONFIG_PWM_TEGRA)         += pwm-tegra.o
 obj-$(CONFIG_PWM_TIECAP)        += pwm-tiecap.o
diff --git a/drivers/pwm/pwm-stmpe.c b/drivers/pwm/pwm-stmpe.c
new file mode 100644
index 000000000000..e464582a390a
--- /dev/null
+++ b/drivers/pwm/pwm-stmpe.c
@@ -0,0 +1,319 @@
+/*
+ * Copyright (C) 2016 Linaro Ltd.
+ *
+ * Author: Linus Walleij <linus.walleij@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/mfd/stmpe.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+#define STMPE24XX_PWMCS         0x30
+#define PWMCS_EN_PWM0           BIT(0)
+#define PWMCS_EN_PWM1           BIT(1)
+#define PWMCS_EN_PWM2           BIT(2)
+#define STMPE24XX_PWMIC0        0x38
+#define STMPE24XX_PWMIC1        0x39
+#define STMPE24XX_PWMIC2        0x3a
+
+#define STMPE_PWM_24XX_PINBASE  21
+
+struct stmpe_pwm {
+        struct stmpe *stmpe;
+        struct pwm_chip chip;
+        u8 last_duty;
+};
+
+static inline struct stmpe_pwm *to_stmpe_pwm(struct pwm_chip *chip)
+{
+        return container_of(chip, struct stmpe_pwm, chip);
+}
+
+static int stmpe_24xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+        struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
+        u8 value;
+        int ret;
+
+        ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS);
+        if (ret < 0) {
+                dev_err(chip->dev, "error reading PWM#%u control\n",
+                        pwm->hwpwm);
+                return ret;
+        }
+
+        value = ret | BIT(pwm->hwpwm);
+
+        ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value);
+        if (ret) {
+                dev_err(chip->dev, "error writing PWM#%u control\n",
+                        pwm->hwpwm);
+                return ret;
+        }
+
+        return 0;
+}
+
+static void stmpe_24xx_pwm_disable(struct pwm_chip *chip,
+                                   struct pwm_device *pwm)
+{
+        struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
+        u8 value;
+        int ret;
+
+        ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS);
+        if (ret < 0) {
+                dev_err(chip->dev, "error reading PWM#%u control\n",
+                        pwm->hwpwm);
+                return;
+        }
+
+        value = ret & ~BIT(pwm->hwpwm);
+
+        ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value);
+        if (ret) {
+                dev_err(chip->dev, "error writing PWM#%u control\n",
+                        pwm->hwpwm);
+                return;
+        }
+}
+
+/* STMPE 24xx PWM instructions */
+#define SMAX            0x007f
+#define SMIN            0x00ff
+#define GTS             0x0000
+#define LOAD            BIT(14) /* Only available on 2403 */
+#define RAMPUP          0x0000
+#define RAMPDOWN        BIT(7)
+#define PRESCALE_512    BIT(14)
+#define STEPTIME_1      BIT(8)
+#define BRANCH          (BIT(15) | BIT(13))
+
+static int stmpe_24xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+                                 int duty_ns, int period_ns)
+{
+        struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
+        unsigned int i, pin;
+        u16 program[3] = {
+                SMAX,
+                GTS,
+                GTS,
+        };
+        u8 offset;
+        int ret;
+
+        /* Make sure we are disabled */
+        if (pwm_is_enabled(pwm)) {
+                stmpe_24xx_pwm_disable(chip, pwm);
+        } else {
+                /* Connect the PWM to the pin */
+                pin = pwm->hwpwm;
+
+                /* On STMPE2401 and 2403 pins 21,22,23 are used */
+                if (stmpe_pwm->stmpe->partnum == STMPE2401 ||
+                    stmpe_pwm->stmpe->partnum == STMPE2403)
+                        pin += STMPE_PWM_24XX_PINBASE;
+
+                ret = stmpe_set_altfunc(stmpe_pwm->stmpe, BIT(pin),
+                                        STMPE_BLOCK_PWM);
+                if (ret) {
+                        dev_err(chip->dev, "unable to connect PWM#%u to pin\n",
+                                pwm->hwpwm);
+                        return ret;
+                }
+        }
+
+        /* STMPE24XX */
+        switch (pwm->hwpwm) {
+        case 0:
+                offset = STMPE24XX_PWMIC0;
+                break;
+
+        case 1:
+                offset = STMPE24XX_PWMIC1;
+                break;
+
+        case 2:
+                offset = STMPE24XX_PWMIC1;
+                break;
+
+        default:
+                /* Should not happen as npwm is 3 */
+                return -ENODEV;
+        }
+
+        dev_dbg(chip->dev, "PWM#%u: config duty %d ns, period %d ns\n",
+                pwm->hwpwm, duty_ns, period_ns);
+
+        if (duty_ns == 0) {
+                if (stmpe_pwm->stmpe->partnum == STMPE2401)
+                        program[0] = SMAX; /* off all the time */
+
+                if (stmpe_pwm->stmpe->partnum == STMPE2403)
+                        program[0] = LOAD | 0xff; /* LOAD 0xff */
+
+                stmpe_pwm->last_duty = 0x00;
+        } else if (duty_ns == period_ns) {
+                if (stmpe_pwm->stmpe->partnum == STMPE2401)
+                        program[0] = SMIN; /* on all the time */
+
+                if (stmpe_pwm->stmpe->partnum == STMPE2403)
+                        program[0] = LOAD | 0x00; /* LOAD 0x00 */
+
+                stmpe_pwm->last_duty = 0xff;
+        } else {
+                u8 value, last = stmpe_pwm->last_duty;
+                unsigned long duty;
+
+                /*
+                 * Counter goes from 0x00 to 0xff repeatedly at 32768 Hz,
+                 * (means a period of 30517 ns) then this is compared to the
+                 * counter from the ramp, if this is >= PWM counter the output
+                 * is high. With LOAD we can define how much of the cycle it
+                 * is on.
+                 *
+                 * Prescale = 0 -> 2 kHz -> T = 1/f = 488281.25 ns
+                 */
+
+                /* Scale to 0..0xff */
+                duty = duty_ns * 256;
+                duty = DIV_ROUND_CLOSEST(duty, period_ns);
+                value = duty;
+
+                if (value == last) {
+                        /* Run the old program */
+                        if (pwm_is_enabled(pwm))
+                                stmpe_24xx_pwm_enable(chip, pwm);
+
+                        return 0;
+                } else if (stmpe_pwm->stmpe->partnum == STMPE2403) {
+                        /* STMPE2403 can simply set the right PWM value */
+                        program[0] = LOAD | value;
+                        program[1] = 0x0000;
+                } else if (stmpe_pwm->stmpe->partnum == STMPE2401) {
+                        /* STMPE2401 need a complex program */
+                        u16 incdec = 0x0000;
+
+                        if (last < value)
+                                /* Count up */
+                                incdec = RAMPUP | (value - last);
+                        else
+                                /* Count down */
+                                incdec = RAMPDOWN | (last - value);
+
+                        /* Step to desired value, smoothly */
+                        program[0] = PRESCALE_512 | STEPTIME_1 | incdec;
+
+                        /* Loop eternally to 0x00 */
+                        program[1] = BRANCH;
+                }
+
+                dev_dbg(chip->dev,
+                        "PWM#%u: value = %02x, last_duty = %02x, program=%04x,%04x,%04x\n",
+                        pwm->hwpwm, value, last, program[0], program[1],
+                        program[2]);
+                stmpe_pwm->last_duty = value;
+        }
+
+        /*
+         * We can write programs of up to 64 16-bit words into this channel.
+         */
+        for (i = 0; i < ARRAY_SIZE(program); i++) {
+                u8 value;
+
+                value = (program[i] >> 8) & 0xff;
+
+                ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value);
+                if (ret) {
+                        dev_err(chip->dev, "error writing register %02x: %d\n",
+                                offset, ret);
+                        return ret;
+                }
+
+                value = program[i] & 0xff;
+
+                ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value);
+                if (ret) {
+                        dev_err(chip->dev, "error writing register %02x: %d\n",
+                                offset, ret);
+                        return ret;
+                }
+        }
+
+        /* If we were enabled, re-enable this PWM */
+        if (pwm_is_enabled(pwm))
+                stmpe_24xx_pwm_enable(chip, pwm);
+
+        /* Sleep for 200ms so we're sure it will take effect */
+        msleep(200);
+
+        dev_dbg(chip->dev, "programmed PWM#%u, %u bytes\n", pwm->hwpwm, i);
+
+        return 0;
+}
+
+static const struct pwm_ops stmpe_24xx_pwm_ops = {
+        .config = stmpe_24xx_pwm_config,
+        .enable = stmpe_24xx_pwm_enable,
+        .disable = stmpe_24xx_pwm_disable,
+        .owner = THIS_MODULE,
+};
+
+static int __init stmpe_pwm_probe(struct platform_device *pdev)
+{
+        struct stmpe *stmpe = dev_get_drvdata(pdev->dev.parent);
+        struct stmpe_pwm *pwm;
+        int ret;
+
+        pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
+        if (!pwm)
+                return -ENOMEM;
+
+        pwm->stmpe = stmpe;
+        pwm->chip.dev = &pdev->dev;
+        pwm->chip.base = -1;
+
+        if (stmpe->partnum == STMPE2401 || stmpe->partnum == STMPE2403) {
+                pwm->chip.ops = &stmpe_24xx_pwm_ops;
+                pwm->chip.npwm = 3;
+        } else {
+                if (stmpe->partnum == STMPE1601)
+                        dev_err(&pdev->dev, "STMPE1601 not yet supported\n");
+                else
+                        dev_err(&pdev->dev, "Unknown STMPE PWM\n");
+
+                return -ENODEV;
+        }
+
+        ret = stmpe_enable(stmpe, STMPE_BLOCK_PWM);
+        if (ret)
+                return ret;
+
+        ret = pwmchip_add(&pwm->chip);
+        if (ret) {
+                stmpe_disable(stmpe, STMPE_BLOCK_PWM);
+                return ret;
+        }
+
+        platform_set_drvdata(pdev, pwm);
+
+        return 0;
+}
+
+static struct platform_driver stmpe_pwm_driver = {
+        .driver = {
+                .name = "stmpe-pwm",
+        },
+};
+builtin_platform_driver_probe(stmpe_pwm_driver, stmpe_pwm_probe);