[PATCH 1/3] pwm: driver for qualcomm ipq6018 pwm block
Devi Priya
quic_devipriy at quicinc.com
Fri Sep 22 03:56:24 PDT 2023
On 9/22/2023 2:05 PM, Baruch Siach wrote:
> Hi Devi,
>
> On Fri, Sep 22 2023, Devi Priya wrote:
>> On 9/15/2023 12:06 PM, Baruch Siach wrote:
>>> Hi Devi,
>>> [ Dropped/updated codeaurora.org addresses ]
>>> On Fri, Sep 15 2023, Devi Priya wrote:
>>>> On 2/7/2022 3:00 PM, Baruch Siach wrote:
>>>>> From: Baruch Siach <baruch.siach at siklu.com>
>>>>> Driver for the PWM block in Qualcomm IPQ6018 line of SoCs. Based on
>>>>> driver from downstream Codeaurora kernel tree. Removed support for older
>>>>> (V1) variants because I have no access to that hardware.
>>>>> Tested on IPQ6010 based hardware.
>>>>> Signed-off-by: Baruch Siach <baruch.siach at siklu.com>
>>>>> ---
>>>>> v11:
>>>>
>>>> Just curious to know if you have plans to post the next revision!
>>> I have been waiting for comments from pwm maintainers before sending the
>>> next revision.
>>> Unfortunately since then I lost access to the hardware, so I can't test
>>> suggested implementation changes. The only pending issue in v11 is the
>>> trivial change that Nathan Chancellor suggested, which should be safe.
>>> If you like to take it from here you are welcome.
>>
>> Could you pls point me to the pending comment that has to be addressed.
>> Was not able to find any open comments in the latest series.
>> https://lore.kernel.org/linux-arm-msm/8a331c88-c7d4-3a14-0ec3-fd616ea24a99@quicinc.com/
>
> See here:
>
> https://lore.kernel.org/all/YgK63cI177ZeF5v1@dev-arch.archlinux-ax161/
Great, thanks!
Devi Priya
>
> baruch
>
>>>>> Address comment from Uwe Kleine-König:
>>>>> Drop redundant registers field comments
>>>>> Fix period limit check in .apply
>>>>> Clarify the comment explaining skip of pre_div > pwm_div values
>>>>> Add explicit check for clock rate within limit
>>>>> Add comment explaining the selection of initial pre_div
>>>>> Use pwm_div division with remainder instead of separate diff calculation
>>>>> Round up duty_cycle calculation in .get_state
>>>>> v10:
>>>>> Restore round up in pwm_div calculation; otherwise diff is always <=
>>>>> 0, so only bingo match works
>>>>> Don't overwrite min_diff on every loop iteration
>>>>> v9:
>>>>> Address comment from Uwe Kleine-König:
>>>>> Use period_ns*rate in dividers calculation for better accuracy
>>>>> Round down pre_div and pwm_div
>>>>> Add a comment explaining why pwm_div can't underflow
>>>>> Add a comment explaining why pre_div > pwm_div end the search loop
>>>>> Drop 'CFG_' from register macros
>>>>> Rename to_ipq_pwm_chip() to ipq_pwm_from_chip()
>>>>> Change bare 'unsigned' to 'unsigned int'
>>>>> Clarify the comment on separate REG1 write for enable/disable
>>>>> Round up the period value in .get_state
>>>>> Use direct readl/writel so no need to check for regmap errors
>>>>> v7:
>>>>> Change 'offset' to 'reg' for the tcsr offset (Rob)
>>>>> Drop clock name; there is only one clock (Bjorn)
>>>>> Simplify probe failure code path (Bjorn)
>>>>> v6:
>>>>> Address Uwe Kleine-König review comments:
>>>>> Drop IPQ_PWM_MAX_DEVICES
>>>>> Rely on assigned-clock-rates; drop IPQ_PWM_CLK_SRC_FREQ
>>>>> Simplify register offset calculation
>>>>> Calculate duty cycle more precisely
>>>>> Refuse to set inverted polarity
>>>>> Drop redundant IPQ_PWM_REG1_ENABLE bit clear
>>>>> Remove x1000 factor in pwm_div calculation, use rate directly, and round
>>>>> up
>>>>> Choose initial pre_div such that pwm_div < IPQ_PWM_MAX_DIV
>>>>> Ensure pre_div <= pwm_div
>>>>> Rename close_ to best_
>>>>> Explain in comment why effective_div doesn't overflow
>>>>> Limit pwm_div to IPQ_PWM_MAX_DIV - 1 to allow 100% duty cycle
>>>>> Disable clock only after pwmchip_remove()
>>>>> const pwm_ops
>>>>> Other changes:
>>>>> Add missing linux/bitfield.h header include (kernel test robot)
>>>>> Adjust code for PWM device node under TCSR (Rob Herring)
>>>>> v5:
>>>>> Use &tcsr_q6 syscon to access registers (Bjorn Andersson)
>>>>> Address Uwe Kleine-König review comments:
>>>>> Implement .get_state()
>>>>> Add IPQ_PWM_ prefix to local macros
>>>>> Use GENMASK/BIT/FIELD_PREP for register fields access
>>>>> Make type of config_div_and_duty() parameters consistent
>>>>> Derive IPQ_PWM_MIN_PERIOD_NS from IPQ_PWM_CLK_SRC_FREQ
>>>>> Integrate enable/disable into config_div_and_duty() to save register
>>>>> read,
>>>>> and reduce frequency glitch on update
>>>>> Use min() instead of min_t()
>>>>> Fix comment format
>>>>> Use dev_err_probe() to indicate probe step failure
>>>>> Add missing clk_disable_unprepare() in .remove
>>>>> Don't set .owner
>>>>> v4:
>>>>> Use div64_u64() to fix link for 32-bit targets ((kernel test robot
>>>>> <lkp at intel.com>, Uwe Kleine-König)
>>>>> v3:
>>>>> s/qcom,pwm-ipq6018/qcom,ipq6018-pwm/ (Rob Herring)
>>>>> Fix integer overflow on 32-bit targets (kernel test robot
>>>>> <lkp at intel.com>)
>>>>> v2:
>>>>> Address Uwe Kleine-König review comments:
>>>>> Fix period calculation when out of range
>>>>> Don't set period larger than requested
>>>>> Remove PWM disable on configuration change
>>>>> Implement .apply instead of non-atomic .config/.enable/.disable
>>>>> Don't modify PWM on .request/.free
>>>>> Check pwm_div underflow
>>>>> Fix various code and comment formatting issues
>>>>> Other changes:
>>>>> Use u64 divisor safe division
>>>>> Remove now empty .request/.free
>>>>> ---
>>>>> drivers/pwm/Kconfig | 12 ++
>>>>> drivers/pwm/Makefile | 1 +
>>>>> drivers/pwm/pwm-ipq.c | 281 ++++++++++++++++++++++++++++++++++++++++++
>>>>> 3 files changed, 294 insertions(+)
>>>>> create mode 100644 drivers/pwm/pwm-ipq.c
>>>>> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
>>>>> index 21e3b05a5153..e39718137ecd 100644
>>>>> --- a/drivers/pwm/Kconfig
>>>>> +++ b/drivers/pwm/Kconfig
>>>>> @@ -260,6 +260,18 @@ config PWM_INTEL_LGM
>>>>> To compile this driver as a module, choose M here: the module
>>>>> will be called pwm-intel-lgm.
>>>>> +config PWM_IPQ
>>>>> + tristate "IPQ PWM support"
>>>>> + depends on ARCH_QCOM || COMPILE_TEST
>>>>> + depends on HAVE_CLK && HAS_IOMEM
>>>>> + help
>>>>> + Generic PWM framework driver for IPQ PWM block which supports
>>>>> + 4 pwm channels. Each of the these channels can be configured
>>>>> + independent of each other.
>>>>> +
>>>>> + To compile this driver as a module, choose M here: the module
>>>>> + will be called pwm-ipq.
>>>>> +
>>>>> config PWM_IQS620A
>>>>> tristate "Azoteq IQS620A PWM support"
>>>>> depends on MFD_IQS62X || COMPILE_TEST
>>>>> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
>>>>> index 708840b7fba8..7402feae4b36 100644
>>>>> --- a/drivers/pwm/Makefile
>>>>> +++ b/drivers/pwm/Makefile
>>>>> @@ -22,6 +22,7 @@ obj-$(CONFIG_PWM_IMX1) += pwm-imx1.o
>>>>> obj-$(CONFIG_PWM_IMX27) += pwm-imx27.o
>>>>> obj-$(CONFIG_PWM_IMX_TPM) += pwm-imx-tpm.o
>>>>> obj-$(CONFIG_PWM_INTEL_LGM) += pwm-intel-lgm.o
>>>>> +obj-$(CONFIG_PWM_IPQ) += pwm-ipq.o
>>>>> obj-$(CONFIG_PWM_IQS620A) += pwm-iqs620a.o
>>>>> obj-$(CONFIG_PWM_JZ4740) += pwm-jz4740.o
>>>>> obj-$(CONFIG_PWM_KEEMBAY) += pwm-keembay.o
>>>>> diff --git a/drivers/pwm/pwm-ipq.c b/drivers/pwm/pwm-ipq.c
>>>>> new file mode 100644
>>>>> index 000000000000..994027290bcb
>>>>> --- /dev/null
>>>>> +++ b/drivers/pwm/pwm-ipq.c
>>>>> @@ -0,0 +1,281 @@
>>>>> +// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
>>>>> +/*
>>>>> + * Copyright (c) 2016-2017, 2020 The Linux Foundation. All rights reserved.
>>>>> + */
>>>>> +
>>>>> +#include <linux/module.h>
>>>>> +#include <linux/platform_device.h>
>>>>> +#include <linux/pwm.h>
>>>>> +#include <linux/clk.h>
>>>>> +#include <linux/io.h>
>>>>> +#include <linux/of.h>
>>>>> +#include <linux/math64.h>
>>>>> +#include <linux/of_device.h>
>>>>> +#include <linux/bitfield.h>
>>>>> +#include <linux/units.h>
>>>>> +
>>>>> +/* The frequency range supported is 1 Hz to clock rate */
>>>>> +#define IPQ_PWM_MAX_PERIOD_NS ((u64)NSEC_PER_SEC)
>>>>> +
>>>>> +/*
>>>>> + * The max value specified for each field is based on the number of bits
>>>>> + * in the pwm control register for that field
>>>>> + */
>>>>> +#define IPQ_PWM_MAX_DIV 0xFFFF
>>>>> +
>>>>> +/*
>>>>> + * Two 32-bit registers for each PWM: REG0, and REG1.
>>>>> + * Base offset for PWM #i is at 8 * #i.
>>>>> + */
>>>>> +#define IPQ_PWM_REG0 0
>>>>> +#define IPQ_PWM_REG0_PWM_DIV GENMASK(15, 0)
>>>>> +#define IPQ_PWM_REG0_HI_DURATION GENMASK(31, 16)
>>>>> +
>>>>> +#define IPQ_PWM_REG1 4
>>>>> +#define IPQ_PWM_REG1_PRE_DIV GENMASK(15, 0)
>>>>> +/*
>>>>> + * Enable bit is set to enable output toggling in pwm device.
>>>>> + * Update bit is set to reflect the changed divider and high duration
>>>>> + * values in register.
>>>>> + */
>>>>> +#define IPQ_PWM_REG1_UPDATE BIT(30)
>>>>> +#define IPQ_PWM_REG1_ENABLE BIT(31)
>>>>> +
>>>>> +
>>>>> +struct ipq_pwm_chip {
>>>>> + struct pwm_chip chip;
>>>>> + struct clk *clk;
>>>>> + void __iomem *mem;
>>>>> +};
>>>>> +
>>>>> +static struct ipq_pwm_chip *ipq_pwm_from_chip(struct pwm_chip *chip)
>>>>> +{
>>>>> + return container_of(chip, struct ipq_pwm_chip, chip);
>>>>> +}
>>>>> +
>>>>> +static unsigned int ipq_pwm_reg_read(struct pwm_device *pwm, unsigned int reg)
>>>>> +{
>>>>> + struct ipq_pwm_chip *ipq_chip = ipq_pwm_from_chip(pwm->chip);
>>>>> + unsigned int off = 8 * pwm->hwpwm + reg;
>>>>> +
>>>>> + return readl(ipq_chip->mem + off);
>>>>> +}
>>>>> +
>>>>> +static void ipq_pwm_reg_write(struct pwm_device *pwm, unsigned int reg,
>>>>> + unsigned int val)
>>>>> +{
>>>>> + struct ipq_pwm_chip *ipq_chip = ipq_pwm_from_chip(pwm->chip);
>>>>> + unsigned int off = 8 * pwm->hwpwm + reg;
>>>>> +
>>>>> + writel(val, ipq_chip->mem + off);
>>>>> +}
>>>>> +
>>>>> +static void config_div_and_duty(struct pwm_device *pwm, unsigned int pre_div,
>>>>> + unsigned int pwm_div, unsigned long rate, u64 duty_ns,
>>>>> + bool enable)
>>>>> +{
>>>>> + unsigned long hi_dur;
>>>>> + unsigned long val = 0;
>>>>> +
>>>>> + /*
>>>>> + * high duration = pwm duty * (pwm div + 1)
>>>>> + * pwm duty = duty_ns / period_ns
>>>>> + */
>>>>> + hi_dur = div64_u64(duty_ns * rate, (pre_div + 1) * NSEC_PER_SEC);
>>>>> +
>>>>> + val = FIELD_PREP(IPQ_PWM_REG0_HI_DURATION, hi_dur) |
>>>>> + FIELD_PREP(IPQ_PWM_REG0_PWM_DIV, pwm_div);
>>>>> + ipq_pwm_reg_write(pwm, IPQ_PWM_REG0, val);
>>>>> +
>>>>> + val = FIELD_PREP(IPQ_PWM_REG1_PRE_DIV, pre_div);
>>>>> + ipq_pwm_reg_write(pwm, IPQ_PWM_REG1, val);
>>>>> +
>>>>> + /* PWM enable toggle needs a separate write to REG1 */
>>>>> + val |= IPQ_PWM_REG1_UPDATE;
>>>>> + if (enable)
>>>>> + val |= IPQ_PWM_REG1_ENABLE;
>>>>> + ipq_pwm_reg_write(pwm, IPQ_PWM_REG1, val);
>>>>> +}
>>>>> +
>>>>> +static int ipq_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>>>>> + const struct pwm_state *state)
>>>>> +{
>>>>> + struct ipq_pwm_chip *ipq_chip = ipq_pwm_from_chip(chip);
>>>>> + unsigned int pre_div, pwm_div, best_pre_div, best_pwm_div;
>>>>> + unsigned long rate = clk_get_rate(ipq_chip->clk);
>>>>> + u64 period_ns, duty_ns, period_rate;
>>>>> + u64 min_diff;
>>>>> +
>>>>> + if (state->polarity != PWM_POLARITY_NORMAL)
>>>>> + return -EINVAL;
>>>>> +
>>>>> + if (state->period < DIV64_U64_ROUND_UP(NSEC_PER_SEC, rate))
>>>>> + return -ERANGE;
>>>>> +
>>>>> + period_ns = min(state->period, IPQ_PWM_MAX_PERIOD_NS);
>>>>> + duty_ns = min(state->duty_cycle, period_ns);
>>>>> +
>>>>> + /*
>>>>> + * period_ns is 1G or less. As long as rate is less than 16 GHz,
>>>>> + * period_rate does not overflow. Make that explicit.
>>>>> + */
>>>>> + if (rate > 16ULL * GIGA)
>>>>> + return -EINVAL;
>>>>> + period_rate = period_ns * rate;
>>>>> + best_pre_div = IPQ_PWM_MAX_DIV;
>>>>> + best_pwm_div = IPQ_PWM_MAX_DIV;
>>>>> + /*
>>>>> + * We don't need to consider pre_div values smaller than
>>>>> + *
>>>>> + * period_rate
>>>>> + * pre_div_min := ------------------------------------
>>>>> + * NSEC_PER_SEC * (IPQ_PWM_MAX_DIV + 1)
>>>>> + *
>>>>> + * because pre_div = pre_div_min results in a better
>>>>> + * approximation.
>>>>> + */
>>>>> + pre_div = div64_u64(period_rate,
>>>>> + (u64)NSEC_PER_SEC * (IPQ_PWM_MAX_DIV + 1));
>>>>> + min_diff = period_rate;
>>>>> +
>>>>> + for (; pre_div <= IPQ_PWM_MAX_DIV; pre_div++) {
>>>>> + u64 remainder;
>>>>> +
>>>>> + pwm_div = div64_u64_rem(period_rate,
>>>>> + (u64)NSEC_PER_SEC * (pre_div + 1), &remainder);
>>>>> + /* pwm_div is unsigned; the check below catches underflow */
>>>>> + pwm_div--;
>>>>> +
>>>>> + /*
>>>>> + * Swapping values for pre_div and pwm_div produces the same
>>>>> + * period length. So we can skip all settings with pre_div >
>>>>> + * pwm_div which results in bigger constraints for selecting
>>>>> + * the duty_cycle than with the two values swapped.
>>>>> + */
>>>>> + if (pre_div > pwm_div)
>>>>> + break;
>>>>> +
>>>>> + /*
>>>>> + * Make sure we can do 100% duty cycle where
>>>>> + * hi_dur == pwm_div + 1
>>>>> + */
>>>>> + if (pwm_div > IPQ_PWM_MAX_DIV - 1)
>>>>> + continue;
>>>>> +
>>>>> + if (remainder < min_diff) {
>>>>> + best_pre_div = pre_div;
>>>>> + best_pwm_div = pwm_div;
>>>>> + min_diff = remainder;
>>>>> +
>>>>> + if (min_diff == 0) /* bingo */
>>>>> + break;
>>>>> + }
>>>>> + }
>>>>> +
>>>>> + /* config divider values for the closest possible frequency */
>>>>> + config_div_and_duty(pwm, best_pre_div, best_pwm_div,
>>>>> + rate, duty_ns, state->enabled);
>>>>> +
>>>>> + return 0;
>>>>> +}
>>>>> +
>>>>> +static void ipq_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
>>>>> + struct pwm_state *state)
>>>>> +{
>>>>> + struct ipq_pwm_chip *ipq_chip = ipq_pwm_from_chip(chip);
>>>>> + unsigned long rate = clk_get_rate(ipq_chip->clk);
>>>>> + unsigned int pre_div, pwm_div, hi_dur;
>>>>> + u64 effective_div, hi_div;
>>>>> + u32 reg0, reg1;
>>>>> +
>>>>> + reg0 = ipq_pwm_reg_read(pwm, IPQ_PWM_REG0);
>>>>> + reg1 = ipq_pwm_reg_read(pwm, IPQ_PWM_REG1);
>>>>> +
>>>>> + state->polarity = PWM_POLARITY_NORMAL;
>>>>> + state->enabled = reg1 & IPQ_PWM_REG1_ENABLE;
>>>>> +
>>>>> + pwm_div = FIELD_GET(IPQ_PWM_REG0_PWM_DIV, reg0);
>>>>> + hi_dur = FIELD_GET(IPQ_PWM_REG0_HI_DURATION, reg0);
>>>>> + pre_div = FIELD_GET(IPQ_PWM_REG1_PRE_DIV, reg1);
>>>>> +
>>>>> + /* No overflow here, both pre_div and pwm_div <= 0xffff */
>>>>> + effective_div = (u64)(pre_div + 1) * (pwm_div + 1);
>>>>> + state->period = DIV64_U64_ROUND_UP(effective_div * NSEC_PER_SEC, rate);
>>>>> +
>>>>> + hi_div = hi_dur * (pre_div + 1);
>>>>> + state->duty_cycle = DIV64_U64_ROUND_UP(hi_div * NSEC_PER_SEC, rate);
>>>>> +}
>>>>> +
>>>>> +static const struct pwm_ops ipq_pwm_ops = {
>>>>> + .apply = ipq_pwm_apply,
>>>>> + .get_state = ipq_pwm_get_state,
>>>>> + .owner = THIS_MODULE,
>>>>> +};
>>>>> +
>>>>> +static int ipq_pwm_probe(struct platform_device *pdev)
>>>>> +{
>>>>> + struct ipq_pwm_chip *pwm;
>>>>> + struct device *dev = &pdev->dev;
>>>>> + int ret;
>>>>> +
>>>>> + pwm = devm_kzalloc(dev, sizeof(*pwm), GFP_KERNEL);
>>>>> + if (!pwm)
>>>>> + return -ENOMEM;
>>>>> +
>>>>> + platform_set_drvdata(pdev, pwm);
>>>>> +
>>>>> + pwm->mem = devm_platform_ioremap_resource(pdev, 0);
>>>>> + if (IS_ERR(pwm->mem))
>>>>> + return dev_err_probe(dev, PTR_ERR(pwm->mem),
>>>>> + "regs map failed");
>>>>> +
>>>>> + pwm->clk = devm_clk_get(dev, NULL);
>>>>> + if (IS_ERR(pwm->clk))
>>>>> + return dev_err_probe(dev, PTR_ERR(pwm->clk),
>>>>> + "failed to get clock");
>>>>> +
>>>>> + ret = clk_prepare_enable(pwm->clk);
>>>>> + if (ret)
>>>>> + return dev_err_probe(dev, ret, "clock enable failed");
>>>>> +
>>>>> + pwm->chip.dev = dev;
>>>>> + pwm->chip.ops = &ipq_pwm_ops;
>>>>> + pwm->chip.npwm = 4;
>>>>> +
>>>>> + ret = pwmchip_add(&pwm->chip);
>>>>> + if (ret < 0) {
>>>>> + dev_err_probe(dev, ret, "pwmchip_add() failed\n");
>>>>> + clk_disable_unprepare(pwm->clk);
>>>>> + }
>>>>> +
>>>>> + return ret;
>>>>> +}
>>>>> +
>>>>> +static int ipq_pwm_remove(struct platform_device *pdev)
>>>>> +{
>>>>> + struct ipq_pwm_chip *pwm = platform_get_drvdata(pdev);
>>>>> +
>>>>> + pwmchip_remove(&pwm->chip);
>>>>> + clk_disable_unprepare(pwm->clk);
>>>>> +
>>>>> + return 0;
>>>>> +}
>>>>> +
>>>>> +static const struct of_device_id pwm_ipq_dt_match[] = {
>>>>> + { .compatible = "qcom,ipq6018-pwm", },
>>>>> + {}
>>>>> +};
>>>>> +MODULE_DEVICE_TABLE(of, pwm_ipq_dt_match);
>>>>> +
>>>>> +static struct platform_driver ipq_pwm_driver = {
>>>>> + .driver = {
>>>>> + .name = "ipq-pwm",
>>>>> + .of_match_table = pwm_ipq_dt_match,
>>>>> + },
>>>>> + .probe = ipq_pwm_probe,
>>>>> + .remove = ipq_pwm_remove,
>>>>> +};
>>>>> +
>>>>> +module_platform_driver(ipq_pwm_driver);
>>>>> +
>>>>> +MODULE_LICENSE("Dual BSD/GPL");
>>>
>
>
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