| // SPDX-License-Identifier: GPL-2.0+ |
| /* |
| * Copyright (C) 2021 Sean Anderson <sean.anderson@seco.com> |
| * |
| * Limitations: |
| * - When changing both duty cycle and period, we may end up with one cycle |
| * with the old duty cycle and the new period. This is because the counters |
| * may only be reloaded by first stopping them, or by letting them be |
| * automatically reloaded at the end of a cycle. If this automatic reload |
| * happens after we set TLR0 but before we set TLR1 then we will have a |
| * bad cycle. This could probably be fixed by reading TCR0 just before |
| * reprogramming, but I think it would add complexity for little gain. |
| * - Cannot produce 100% duty cycle by configuring the TLRs. This might be |
| * possible by stopping the counters at an appropriate point in the cycle, |
| * but this is not (yet) implemented. |
| * - Only produces "normal" output. |
| * - Always produces low output if disabled. |
| */ |
| |
| #include <clocksource/timer-xilinx.h> |
| #include <linux/clk.h> |
| #include <linux/clk-provider.h> |
| #include <linux/device.h> |
| #include <linux/module.h> |
| #include <linux/of.h> |
| #include <linux/platform_device.h> |
| #include <linux/pwm.h> |
| #include <linux/regmap.h> |
| |
| /* |
| * The following functions are "common" to drivers for this device, and may be |
| * exported at a future date. |
| */ |
| u32 xilinx_timer_tlr_cycles(struct xilinx_timer_priv *priv, u32 tcsr, |
| u64 cycles) |
| { |
| WARN_ON(cycles < 2 || cycles - 2 > priv->max); |
| |
| if (tcsr & TCSR_UDT) |
| return cycles - 2; |
| return priv->max - cycles + 2; |
| } |
| |
| unsigned int xilinx_timer_get_period(struct xilinx_timer_priv *priv, |
| u32 tlr, u32 tcsr) |
| { |
| u64 cycles; |
| |
| if (tcsr & TCSR_UDT) |
| cycles = tlr + 2; |
| else |
| cycles = (u64)priv->max - tlr + 2; |
| |
| /* cycles has a max of 2^32 + 2, so we can't overflow */ |
| return DIV64_U64_ROUND_UP(cycles * NSEC_PER_SEC, |
| clk_get_rate(priv->clk)); |
| } |
| |
| /* |
| * The idea here is to capture whether the PWM is actually running (e.g. |
| * because we or the bootloader set it up) and we need to be careful to ensure |
| * we don't cause a glitch. According to the data sheet, to enable the PWM we |
| * need to |
| * |
| * - Set both timers to generate mode (MDT=1) |
| * - Set both timers to PWM mode (PWMA=1) |
| * - Enable the generate out signals (GENT=1) |
| * |
| * In addition, |
| * |
| * - The timer must be running (ENT=1) |
| * - The timer must auto-reload TLR into TCR (ARHT=1) |
| * - We must not be in the process of loading TLR into TCR (LOAD=0) |
| * - Cascade mode must be disabled (CASC=0) |
| * |
| * If any of these differ from usual, then the PWM is either disabled, or is |
| * running in a mode that this driver does not support. |
| */ |
| #define TCSR_PWM_SET (TCSR_GENT | TCSR_ARHT | TCSR_ENT | TCSR_PWMA) |
| #define TCSR_PWM_CLEAR (TCSR_MDT | TCSR_LOAD) |
| #define TCSR_PWM_MASK (TCSR_PWM_SET | TCSR_PWM_CLEAR) |
| |
| static inline struct xilinx_timer_priv |
| *xilinx_pwm_chip_to_priv(struct pwm_chip *chip) |
| { |
| return pwmchip_get_drvdata(chip); |
| } |
| |
| static bool xilinx_timer_pwm_enabled(u32 tcsr0, u32 tcsr1) |
| { |
| return ((TCSR_PWM_MASK | TCSR_CASC) & tcsr0) == TCSR_PWM_SET && |
| (TCSR_PWM_MASK & tcsr1) == TCSR_PWM_SET; |
| } |
| |
| static int xilinx_pwm_apply(struct pwm_chip *chip, struct pwm_device *unused, |
| const struct pwm_state *state) |
| { |
| struct xilinx_timer_priv *priv = xilinx_pwm_chip_to_priv(chip); |
| u32 tlr0, tlr1, tcsr0, tcsr1; |
| u64 period_cycles, duty_cycles; |
| unsigned long rate; |
| |
| if (state->polarity != PWM_POLARITY_NORMAL) |
| return -EINVAL; |
| |
| /* |
| * To be representable by TLR, cycles must be between 2 and |
| * priv->max + 2. To enforce this we can reduce the cycles, but we may |
| * not increase them. Caveat emptor: while this does result in more |
| * predictable rounding, it may also result in a completely different |
| * duty cycle (% high time) than what was requested. |
| */ |
| rate = clk_get_rate(priv->clk); |
| /* Avoid overflow */ |
| period_cycles = min_t(u64, state->period, U32_MAX * NSEC_PER_SEC); |
| period_cycles = mul_u64_u32_div(period_cycles, rate, NSEC_PER_SEC); |
| period_cycles = min_t(u64, period_cycles, priv->max + 2); |
| if (period_cycles < 2) |
| return -ERANGE; |
| |
| /* Same thing for duty cycles */ |
| duty_cycles = min_t(u64, state->duty_cycle, U32_MAX * NSEC_PER_SEC); |
| duty_cycles = mul_u64_u32_div(duty_cycles, rate, NSEC_PER_SEC); |
| duty_cycles = min_t(u64, duty_cycles, priv->max + 2); |
| |
| /* |
| * If we specify 100% duty cycle, we will get 0% instead, so decrease |
| * the duty cycle count by one. |
| */ |
| if (duty_cycles >= period_cycles) |
| duty_cycles = period_cycles - 1; |
| |
| /* Round down to 0% duty cycle for unrepresentable duty cycles */ |
| if (duty_cycles < 2) |
| duty_cycles = period_cycles; |
| |
| regmap_read(priv->map, TCSR0, &tcsr0); |
| regmap_read(priv->map, TCSR1, &tcsr1); |
| tlr0 = xilinx_timer_tlr_cycles(priv, tcsr0, period_cycles); |
| tlr1 = xilinx_timer_tlr_cycles(priv, tcsr1, duty_cycles); |
| regmap_write(priv->map, TLR0, tlr0); |
| regmap_write(priv->map, TLR1, tlr1); |
| |
| if (state->enabled) { |
| /* |
| * If the PWM is already running, then the counters will be |
| * reloaded at the end of the current cycle. |
| */ |
| if (!xilinx_timer_pwm_enabled(tcsr0, tcsr1)) { |
| /* Load TLR into TCR */ |
| regmap_write(priv->map, TCSR0, tcsr0 | TCSR_LOAD); |
| regmap_write(priv->map, TCSR1, tcsr1 | TCSR_LOAD); |
| /* Enable timers all at once with ENALL */ |
| tcsr0 = (TCSR_PWM_SET & ~TCSR_ENT) | (tcsr0 & TCSR_UDT); |
| tcsr1 = TCSR_PWM_SET | TCSR_ENALL | (tcsr1 & TCSR_UDT); |
| regmap_write(priv->map, TCSR0, tcsr0); |
| regmap_write(priv->map, TCSR1, tcsr1); |
| } |
| } else { |
| regmap_write(priv->map, TCSR0, 0); |
| regmap_write(priv->map, TCSR1, 0); |
| } |
| |
| return 0; |
| } |
| |
| static int xilinx_pwm_get_state(struct pwm_chip *chip, |
| struct pwm_device *unused, |
| struct pwm_state *state) |
| { |
| struct xilinx_timer_priv *priv = xilinx_pwm_chip_to_priv(chip); |
| u32 tlr0, tlr1, tcsr0, tcsr1; |
| |
| regmap_read(priv->map, TLR0, &tlr0); |
| regmap_read(priv->map, TLR1, &tlr1); |
| regmap_read(priv->map, TCSR0, &tcsr0); |
| regmap_read(priv->map, TCSR1, &tcsr1); |
| state->period = xilinx_timer_get_period(priv, tlr0, tcsr0); |
| state->duty_cycle = xilinx_timer_get_period(priv, tlr1, tcsr1); |
| state->enabled = xilinx_timer_pwm_enabled(tcsr0, tcsr1); |
| state->polarity = PWM_POLARITY_NORMAL; |
| |
| /* |
| * 100% duty cycle results in constant low output. This may be (very) |
| * wrong if rate > 1 GHz, so fix this if you have such hardware :) |
| */ |
| if (state->period == state->duty_cycle) |
| state->duty_cycle = 0; |
| |
| return 0; |
| } |
| |
| static const struct pwm_ops xilinx_pwm_ops = { |
| .apply = xilinx_pwm_apply, |
| .get_state = xilinx_pwm_get_state, |
| }; |
| |
| static const struct regmap_config xilinx_pwm_regmap_config = { |
| .reg_bits = 32, |
| .reg_stride = 4, |
| .val_bits = 32, |
| .val_format_endian = REGMAP_ENDIAN_LITTLE, |
| .max_register = TCR1, |
| }; |
| |
| static int xilinx_pwm_probe(struct platform_device *pdev) |
| { |
| int ret; |
| struct device *dev = &pdev->dev; |
| struct device_node *np = dev->of_node; |
| struct xilinx_timer_priv *priv; |
| struct pwm_chip *chip; |
| u32 pwm_cells, one_timer, width; |
| void __iomem *regs; |
| |
| /* If there are no PWM cells, this binding is for a timer */ |
| ret = of_property_read_u32(np, "#pwm-cells", &pwm_cells); |
| if (ret == -EINVAL) |
| return -ENODEV; |
| if (ret) |
| return dev_err_probe(dev, ret, "could not read #pwm-cells\n"); |
| |
| chip = devm_pwmchip_alloc(dev, 1, sizeof(*priv)); |
| if (IS_ERR(chip)) |
| return PTR_ERR(chip); |
| priv = xilinx_pwm_chip_to_priv(chip); |
| platform_set_drvdata(pdev, chip); |
| |
| regs = devm_platform_ioremap_resource(pdev, 0); |
| if (IS_ERR(regs)) |
| return PTR_ERR(regs); |
| |
| priv->map = devm_regmap_init_mmio(dev, regs, |
| &xilinx_pwm_regmap_config); |
| if (IS_ERR(priv->map)) |
| return dev_err_probe(dev, PTR_ERR(priv->map), |
| "Could not create regmap\n"); |
| |
| ret = of_property_read_u32(np, "xlnx,one-timer-only", &one_timer); |
| if (ret) |
| return dev_err_probe(dev, ret, |
| "Could not read xlnx,one-timer-only\n"); |
| |
| if (one_timer) |
| return dev_err_probe(dev, -EINVAL, |
| "Two timers required for PWM mode\n"); |
| |
| ret = of_property_read_u32(np, "xlnx,count-width", &width); |
| if (ret == -EINVAL) |
| width = 32; |
| else if (ret) |
| return dev_err_probe(dev, ret, |
| "Could not read xlnx,count-width\n"); |
| |
| if (width != 8 && width != 16 && width != 32) |
| return dev_err_probe(dev, -EINVAL, |
| "Invalid counter width %d\n", width); |
| priv->max = BIT_ULL(width) - 1; |
| |
| /* |
| * The polarity of the Generate Out signals must be active high for PWM |
| * mode to work. We could determine this from the device tree, but |
| * alas, such properties are not allowed to be used. |
| */ |
| |
| priv->clk = devm_clk_get(dev, "s_axi_aclk"); |
| if (IS_ERR(priv->clk)) |
| return dev_err_probe(dev, PTR_ERR(priv->clk), |
| "Could not get clock\n"); |
| |
| ret = clk_prepare_enable(priv->clk); |
| if (ret) |
| return dev_err_probe(dev, ret, "Clock enable failed\n"); |
| clk_rate_exclusive_get(priv->clk); |
| |
| chip->ops = &xilinx_pwm_ops; |
| ret = pwmchip_add(chip); |
| if (ret) { |
| clk_rate_exclusive_put(priv->clk); |
| clk_disable_unprepare(priv->clk); |
| return dev_err_probe(dev, ret, "Could not register PWM chip\n"); |
| } |
| |
| return 0; |
| } |
| |
| static void xilinx_pwm_remove(struct platform_device *pdev) |
| { |
| struct pwm_chip *chip = platform_get_drvdata(pdev); |
| struct xilinx_timer_priv *priv = xilinx_pwm_chip_to_priv(chip); |
| |
| pwmchip_remove(chip); |
| clk_rate_exclusive_put(priv->clk); |
| clk_disable_unprepare(priv->clk); |
| } |
| |
| static const struct of_device_id xilinx_pwm_of_match[] = { |
| { .compatible = "xlnx,xps-timer-1.00.a", }, |
| {}, |
| }; |
| MODULE_DEVICE_TABLE(of, xilinx_pwm_of_match); |
| |
| static struct platform_driver xilinx_pwm_driver = { |
| .probe = xilinx_pwm_probe, |
| .remove_new = xilinx_pwm_remove, |
| .driver = { |
| .name = "xilinx-pwm", |
| .of_match_table = of_match_ptr(xilinx_pwm_of_match), |
| }, |
| }; |
| module_platform_driver(xilinx_pwm_driver); |
| |
| MODULE_ALIAS("platform:xilinx-pwm"); |
| MODULE_DESCRIPTION("PWM driver for Xilinx LogiCORE IP AXI Timer"); |
| MODULE_LICENSE("GPL"); |