drivers/clocksource/timer-stm32-lp.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) STMicroelectronics 2019 - All Rights Reserved
   4  * Authors: Benjamin Gaignard <benjamin.gaignard@st.com> for STMicroelectronics.
   5  *          Pascal Paillet <p.paillet@st.com> for STMicroelectronics.
   6  */
   7
   8 #include <linux/clk.h>
   9 #include <linux/clockchips.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/mfd/stm32-lptimer.h>
  12 #include <linux/module.h>
  13 #include <linux/of_address.h>
  14 #include <linux/of_irq.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/pm_wakeirq.h>
  17
  18 #define CFGR_PSC_OFFSET         9
  19 #define STM32_LP_RATING         1000
  20 #define STM32_TARGET_CLKRATE    (32000 * HZ)
  21 #define STM32_LP_MAX_PSC        7
  22
  23 struct stm32_lp_private {
  24         struct regmap *reg;
  25         struct clock_event_device clkevt;
  26         unsigned long period;
  27         struct device *dev;
  28 };
  29
  30 static struct stm32_lp_private*
  31 to_priv(struct clock_event_device *clkevt)
  32 {
  33         return container_of(clkevt, struct stm32_lp_private, clkevt);
  34 }
  35
  36 static int stm32_clkevent_lp_shutdown(struct clock_event_device *clkevt)
  37 {
  38         struct stm32_lp_private *priv = to_priv(clkevt);
  39
  40         regmap_write(priv->reg, STM32_LPTIM_CR, 0);
  41         regmap_write(priv->reg, STM32_LPTIM_IER, 0);
  42         /* clear pending flags */
  43         regmap_write(priv->reg, STM32_LPTIM_ICR, STM32_LPTIM_ARRMCF);
  44
  45         return 0;
  46 }
  47
  48 static int stm32_clkevent_lp_set_timer(unsigned long evt,
  49                                        struct clock_event_device *clkevt,
  50                                        int is_periodic)
  51 {
  52         struct stm32_lp_private *priv = to_priv(clkevt);
  53
  54         /* disable LPTIMER to be able to write into IER register*/
  55         regmap_write(priv->reg, STM32_LPTIM_CR, 0);
  56         /* enable ARR interrupt */
  57         regmap_write(priv->reg, STM32_LPTIM_IER, STM32_LPTIM_ARRMIE);
  58         /* enable LPTIMER to be able to write into ARR register */
  59         regmap_write(priv->reg, STM32_LPTIM_CR, STM32_LPTIM_ENABLE);
  60         /* set next event counter */
  61         regmap_write(priv->reg, STM32_LPTIM_ARR, evt);
  62
  63         /* start counter */
  64         if (is_periodic)
  65                 regmap_write(priv->reg, STM32_LPTIM_CR,
  66                              STM32_LPTIM_CNTSTRT | STM32_LPTIM_ENABLE);
  67         else
  68                 regmap_write(priv->reg, STM32_LPTIM_CR,
  69                              STM32_LPTIM_SNGSTRT | STM32_LPTIM_ENABLE);
  70
  71         return 0;
  72 }
  73
  74 static int stm32_clkevent_lp_set_next_event(unsigned long evt,
  75                                             struct clock_event_device *clkevt)
  76 {
  77         return stm32_clkevent_lp_set_timer(evt, clkevt,
  78                                            clockevent_state_periodic(clkevt));
  79 }
  80
  81 static int stm32_clkevent_lp_set_periodic(struct clock_event_device *clkevt)
  82 {
  83         struct stm32_lp_private *priv = to_priv(clkevt);
  84
  85         return stm32_clkevent_lp_set_timer(priv->period, clkevt, true);
  86 }
  87
  88 static int stm32_clkevent_lp_set_oneshot(struct clock_event_device *clkevt)
  89 {
  90         struct stm32_lp_private *priv = to_priv(clkevt);
  91
  92         return stm32_clkevent_lp_set_timer(priv->period, clkevt, false);
  93 }
  94
  95 static irqreturn_t stm32_clkevent_lp_irq_handler(int irq, void *dev_id)
  96 {
  97         struct clock_event_device *clkevt = (struct clock_event_device *)dev_id;
  98         struct stm32_lp_private *priv = to_priv(clkevt);
  99
 100         regmap_write(priv->reg, STM32_LPTIM_ICR, STM32_LPTIM_ARRMCF);
 101
 102         if (clkevt->event_handler)
 103                 clkevt->event_handler(clkevt);
 104
 105         return IRQ_HANDLED;
 106 }
 107
 108 static void stm32_clkevent_lp_set_prescaler(struct stm32_lp_private *priv,
 109                                             unsigned long *rate)
 110 {
 111         int i;
 112
 113         for (i = 0; i <= STM32_LP_MAX_PSC; i++) {
 114                 if (DIV_ROUND_CLOSEST(*rate, 1 << i) < STM32_TARGET_CLKRATE)
 115                         break;
 116         }
 117
 118         regmap_write(priv->reg, STM32_LPTIM_CFGR, i << CFGR_PSC_OFFSET);
 119
 120         /* Adjust rate and period given the prescaler value */
 121         *rate = DIV_ROUND_CLOSEST(*rate, (1 << i));
 122         priv->period = DIV_ROUND_UP(*rate, HZ);
 123 }
 124
 125 static void stm32_clkevent_lp_init(struct stm32_lp_private *priv,
 126                                   struct device_node *np, unsigned long rate)
 127 {
 128         priv->clkevt.name = np->full_name;
 129         priv->clkevt.cpumask = cpu_possible_mask;
 130         priv->clkevt.features = CLOCK_EVT_FEAT_PERIODIC |
 131                                 CLOCK_EVT_FEAT_ONESHOT;
 132         priv->clkevt.set_state_shutdown = stm32_clkevent_lp_shutdown;
 133         priv->clkevt.set_state_periodic = stm32_clkevent_lp_set_periodic;
 134         priv->clkevt.set_state_oneshot = stm32_clkevent_lp_set_oneshot;
 135         priv->clkevt.set_next_event = stm32_clkevent_lp_set_next_event;
 136         priv->clkevt.rating = STM32_LP_RATING;
 137
 138         clockevents_config_and_register(&priv->clkevt, rate, 0x1,
 139                                         STM32_LPTIM_MAX_ARR);
 140 }
 141
 142 static int stm32_clkevent_lp_probe(struct platform_device *pdev)
 143 {
 144         struct stm32_lptimer *ddata = dev_get_drvdata(pdev->dev.parent);
 145         struct stm32_lp_private *priv;
 146         unsigned long rate;
 147         int ret, irq;
 148
 149         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 150         if (!priv)
 151                 return -ENOMEM;
 152
 153         priv->reg = ddata->regmap;
 154         ret = clk_prepare_enable(ddata->clk);
 155         if (ret)
 156                 return -EINVAL;
 157
 158         rate = clk_get_rate(ddata->clk);
 159         if (!rate) {
 160                 ret = -EINVAL;
 161                 goto out_clk_disable;
 162         }
 163
 164         irq = platform_get_irq(to_platform_device(pdev->dev.parent), 0);
 165         if (irq <= 0) {
 166                 ret = irq;
 167                 goto out_clk_disable;
 168         }
 169
 170         if (of_property_read_bool(pdev->dev.parent->of_node, "wakeup-source")) {
 171                 ret = device_init_wakeup(&pdev->dev, true);
 172                 if (ret)
 173                         goto out_clk_disable;
 174
 175                 ret = dev_pm_set_wake_irq(&pdev->dev, irq);
 176                 if (ret)
 177                         goto out_clk_disable;
 178         }
 179
 180         ret = devm_request_irq(&pdev->dev, irq, stm32_clkevent_lp_irq_handler,
 181                                IRQF_TIMER, pdev->name, &priv->clkevt);
 182         if (ret)
 183                 goto out_clk_disable;
 184
 185         stm32_clkevent_lp_set_prescaler(priv, &rate);
 186
 187         stm32_clkevent_lp_init(priv, pdev->dev.parent->of_node, rate);
 188
 189         priv->dev = &pdev->dev;
 190
 191         return 0;
 192
 193 out_clk_disable:
 194         clk_disable_unprepare(ddata->clk);
 195         return ret;
 196 }
 197
 198 static int stm32_clkevent_lp_remove(struct platform_device *pdev)
 199 {
 200         return -EBUSY; /* cannot unregister clockevent */
 201 }
 202
 203 static const struct of_device_id stm32_clkevent_lp_of_match[] = {
 204         { .compatible = "st,stm32-lptimer-timer", },
 205         {},
 206 };
 207 MODULE_DEVICE_TABLE(of, stm32_clkevent_lp_of_match);
 208
 209 static struct platform_driver stm32_clkevent_lp_driver = {
 210         .probe  = stm32_clkevent_lp_probe,
 211         .remove = stm32_clkevent_lp_remove,
 212         .driver = {
 213                 .name = "stm32-lptimer-timer",
 214                 .of_match_table = of_match_ptr(stm32_clkevent_lp_of_match),
 215         },
 216 };
 217 module_platform_driver(stm32_clkevent_lp_driver);
 218
 219 MODULE_ALIAS("platform:stm32-lptimer-timer");
 220 MODULE_DESCRIPTION("STMicroelectronics STM32 clockevent low power driver");
 221 MODULE_LICENSE("GPL v2");