diff options
Diffstat (limited to 'drivers/pwm/pwm-tiecap.c')
| -rw-r--r-- | drivers/pwm/pwm-tiecap.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-tiecap.c b/drivers/pwm/pwm-tiecap.c new file mode 100644 index 00000000000..0b66d0f2592 --- /dev/null +++ b/drivers/pwm/pwm-tiecap.c @@ -0,0 +1,230 @@ +/* + * ECAP PWM driver + * + * Copyright (C) 2012 Texas Instruments, Inc. - http://www.ti.com/ + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/io.h> +#include <linux/err.h> +#include <linux/clk.h> +#include <linux/pm_runtime.h> +#include <linux/pwm.h> + +/* ECAP registers and bits definitions */ +#define CAP1 0x08 +#define CAP2 0x0C +#define CAP3 0x10 +#define CAP4 0x14 +#define ECCTL2 0x2A +#define ECCTL2_APWM_MODE BIT(9) +#define ECCTL2_SYNC_SEL_DISA (BIT(7) | BIT(6)) +#define ECCTL2_TSCTR_FREERUN BIT(4) + +struct ecap_pwm_chip { + struct pwm_chip chip; + unsigned int clk_rate; + void __iomem *mmio_base; +}; + +static inline struct ecap_pwm_chip *to_ecap_pwm_chip(struct pwm_chip *chip) +{ + return container_of(chip, struct ecap_pwm_chip, chip); +} + +/* + * period_ns = 10^9 * period_cycles / PWM_CLK_RATE + * duty_ns = 10^9 * duty_cycles / PWM_CLK_RATE + */ +static int ecap_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, + int duty_ns, int period_ns) +{ + struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); + unsigned long long c; + unsigned long period_cycles, duty_cycles; + unsigned int reg_val; + + if (period_ns < 0 || duty_ns < 0 || period_ns > NSEC_PER_SEC) + return -ERANGE; + + c = pc->clk_rate; + c = c * period_ns; + do_div(c, NSEC_PER_SEC); + period_cycles = (unsigned long)c; + + if (period_cycles < 1) { + period_cycles = 1; + duty_cycles = 1; + } else { + c = pc->clk_rate; + c = c * duty_ns; + do_div(c, NSEC_PER_SEC); + duty_cycles = (unsigned long)c; + } + + pm_runtime_get_sync(pc->chip.dev); + + reg_val = readw(pc->mmio_base + ECCTL2); + + /* Configure APWM mode & disable sync option */ + reg_val |= ECCTL2_APWM_MODE | ECCTL2_SYNC_SEL_DISA; + + writew(reg_val, pc->mmio_base + ECCTL2); + + if (!test_bit(PWMF_ENABLED, &pwm->flags)) { + /* Update active registers if not running */ + writel(duty_cycles, pc->mmio_base + CAP2); + writel(period_cycles, pc->mmio_base + CAP1); + } else { + /* + * Update shadow registers to configure period and + * compare values. This helps current PWM period to + * complete on reconfiguring + */ + writel(duty_cycles, pc->mmio_base + CAP4); + writel(period_cycles, pc->mmio_base + CAP3); + } + + pm_runtime_put_sync(pc->chip.dev); + return 0; +} + +static int ecap_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); + unsigned int reg_val; + + /* Leave clock enabled on enabling PWM */ + pm_runtime_get_sync(pc->chip.dev); + + /* + * Enable 'Free run Time stamp counter mode' to start counter + * and 'APWM mode' to enable APWM output + */ + reg_val = readw(pc->mmio_base + ECCTL2); + reg_val |= ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE; + writew(reg_val, pc->mmio_base + ECCTL2); + return 0; +} + +static void ecap_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); + unsigned int reg_val; + + /* + * Disable 'Free run Time stamp counter mode' to stop counter + * and 'APWM mode' to put APWM output to low + */ + reg_val = readw(pc->mmio_base + ECCTL2); + reg_val &= ~(ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE); + writew(reg_val, pc->mmio_base + ECCTL2); + + /* Disable clock on PWM disable */ + pm_runtime_put_sync(pc->chip.dev); +} + +static void ecap_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) +{ + if (test_bit(PWMF_ENABLED, &pwm->flags)) { + dev_warn(chip->dev, "Removing PWM device without disabling\n"); + pm_runtime_put_sync(chip->dev); + } +} + +static const struct pwm_ops ecap_pwm_ops = { + .free = ecap_pwm_free, + .config = ecap_pwm_config, + .enable = ecap_pwm_enable, + .disable = ecap_pwm_disable, + .owner = THIS_MODULE, +}; + +static int __devinit ecap_pwm_probe(struct platform_device *pdev) +{ + int ret; + struct resource *r; + struct clk *clk; + struct ecap_pwm_chip *pc; + + pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL); + if (!pc) { + dev_err(&pdev->dev, "failed to allocate memory\n"); + return -ENOMEM; + } + + clk = devm_clk_get(&pdev->dev, "fck"); + if (IS_ERR(clk)) { + dev_err(&pdev->dev, "failed to get clock\n"); + return PTR_ERR(clk); + } + + pc->clk_rate = clk_get_rate(clk); + if (!pc->clk_rate) { + dev_err(&pdev->dev, "failed to get clock rate\n"); + return -EINVAL; + } + + pc->chip.dev = &pdev->dev; + pc->chip.ops = &ecap_pwm_ops; + pc->chip.base = -1; + pc->chip.npwm = 1; + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!r) { + dev_err(&pdev->dev, "no memory resource defined\n"); + return -ENODEV; + } + + pc->mmio_base = devm_request_and_ioremap(&pdev->dev, r); + if (!pc->mmio_base) + return -EADDRNOTAVAIL; + + ret = pwmchip_add(&pc->chip); + if (ret < 0) { + dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret); + return ret; + } + + pm_runtime_enable(&pdev->dev); + platform_set_drvdata(pdev, pc); + return 0; +} + +static int __devexit ecap_pwm_remove(struct platform_device *pdev) +{ + struct ecap_pwm_chip *pc = platform_get_drvdata(pdev); + + pm_runtime_put_sync(&pdev->dev); + pm_runtime_disable(&pdev->dev); + return pwmchip_remove(&pc->chip); +} + +static struct platform_driver ecap_pwm_driver = { + .driver = { + .name = "ecap", + }, + .probe = ecap_pwm_probe, + .remove = __devexit_p(ecap_pwm_remove), +}; + +module_platform_driver(ecap_pwm_driver); + +MODULE_DESCRIPTION("ECAP PWM driver"); +MODULE_AUTHOR("Texas Instruments"); +MODULE_LICENSE("GPL"); |