mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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1e185c7aaf
Commit 76abbdde2d
pwm: Add sysfs interface
causes a kernel oops due to a null pointer dereference on PXA platforms.
This happens because the class added by the patch is registered in a
subsys_initcall (initcall4), but the pxa pwm driver is registered in
arch_initcall (initcall3). If the class is not registered before the
driver probe function runs, the oops occurs in device_add() when the
uninitialized pointers in struct class are dereferenced. I don't see a
reason that the driver must be an arch_initcall, so this patch makes it
a regular module_platform_driver (initcall6), preventing the oops.
Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
188 lines
4.2 KiB
C
188 lines
4.2 KiB
C
/*
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* drivers/pwm/pwm-pxa.c
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*
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* simple driver for PWM (Pulse Width Modulator) controller
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* 2008-02-13 initial version
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* eric miao <eric.miao@marvell.com>
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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#include <linux/err.h>
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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 <asm/div64.h>
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#define HAS_SECONDARY_PWM 0x10
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static const struct platform_device_id pwm_id_table[] = {
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/* PWM has_secondary_pwm? */
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{ "pxa25x-pwm", 0 },
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{ "pxa27x-pwm", HAS_SECONDARY_PWM },
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{ "pxa168-pwm", 0 },
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{ "pxa910-pwm", 0 },
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{ },
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};
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MODULE_DEVICE_TABLE(platform, pwm_id_table);
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/* PWM registers and bits definitions */
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#define PWMCR (0x00)
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#define PWMDCR (0x04)
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#define PWMPCR (0x08)
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#define PWMCR_SD (1 << 6)
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#define PWMDCR_FD (1 << 10)
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struct pxa_pwm_chip {
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struct pwm_chip chip;
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struct device *dev;
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struct clk *clk;
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void __iomem *mmio_base;
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};
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static inline struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip)
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{
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return container_of(chip, struct pxa_pwm_chip, chip);
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}
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/*
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* period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
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* duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
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*/
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static int pxa_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
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int duty_ns, int period_ns)
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{
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struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
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unsigned long long c;
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unsigned long period_cycles, prescale, pv, dc;
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unsigned long offset;
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int rc;
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offset = pwm->hwpwm ? 0x10 : 0;
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c = clk_get_rate(pc->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 (period_cycles < 1)
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period_cycles = 1;
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prescale = (period_cycles - 1) / 1024;
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pv = period_cycles / (prescale + 1) - 1;
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if (prescale > 63)
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return -EINVAL;
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if (duty_ns == period_ns)
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dc = PWMDCR_FD;
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else
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dc = (pv + 1) * duty_ns / period_ns;
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/* NOTE: the clock to PWM has to be enabled first
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* before writing to the registers
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*/
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rc = clk_prepare_enable(pc->clk);
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if (rc < 0)
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return rc;
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writel(prescale, pc->mmio_base + offset + PWMCR);
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writel(dc, pc->mmio_base + offset + PWMDCR);
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writel(pv, pc->mmio_base + offset + PWMPCR);
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clk_disable_unprepare(pc->clk);
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return 0;
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}
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static int pxa_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
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return clk_prepare_enable(pc->clk);
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}
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static void pxa_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
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clk_disable_unprepare(pc->clk);
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}
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static struct pwm_ops pxa_pwm_ops = {
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.config = pxa_pwm_config,
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.enable = pxa_pwm_enable,
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.disable = pxa_pwm_disable,
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.owner = THIS_MODULE,
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};
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static int pwm_probe(struct platform_device *pdev)
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{
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const struct platform_device_id *id = platform_get_device_id(pdev);
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struct pxa_pwm_chip *pwm;
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struct resource *r;
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int ret = 0;
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pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
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if (pwm == NULL) {
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dev_err(&pdev->dev, "failed to allocate memory\n");
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return -ENOMEM;
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}
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pwm->clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(pwm->clk))
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return PTR_ERR(pwm->clk);
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pwm->chip.dev = &pdev->dev;
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pwm->chip.ops = &pxa_pwm_ops;
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pwm->chip.base = -1;
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pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
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if (IS_ERR(pwm->mmio_base))
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return PTR_ERR(pwm->mmio_base);
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ret = pwmchip_add(&pwm->chip);
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if (ret < 0) {
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dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
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return ret;
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}
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platform_set_drvdata(pdev, pwm);
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return 0;
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}
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static int pwm_remove(struct platform_device *pdev)
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{
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struct pxa_pwm_chip *chip;
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chip = platform_get_drvdata(pdev);
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if (chip == NULL)
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return -ENODEV;
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return pwmchip_remove(&chip->chip);
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}
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static struct platform_driver pwm_driver = {
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.driver = {
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.name = "pxa25x-pwm",
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.owner = THIS_MODULE,
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},
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.probe = pwm_probe,
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.remove = pwm_remove,
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.id_table = pwm_id_table,
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};
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module_platform_driver(pwm_driver);
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MODULE_LICENSE("GPL v2");
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