[PATCH 1/3] pwm: driver for qualcomm ipq6018 pwm block
Baruch Siach
baruch at tkos.co.il
Mon Feb 7 01:30:43 PST 2022
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:
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");
--
2.34.1
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