1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Real time clocks driver for MStar/SigmaStar ARMv7 SoCs. 4 * Based on "Real Time Clock driver for msb252x." that was contained 5 * in various MStar kernels. 6 * 7 * (C) 2019 Daniel Palmer 8 * (C) 2021 Romain Perier 9 */ 10 11 #include <linux/clk.h> 12 #include <linux/delay.h> 13 #include <linux/io.h> 14 #include <linux/module.h> 15 #include <linux/mod_devicetable.h> 16 #include <linux/platform_device.h> 17 #include <linux/rtc.h> 18 19 /* Registers */ 20 #define REG_RTC_CTRL 0x00 21 #define REG_RTC_FREQ_CW_L 0x04 22 #define REG_RTC_FREQ_CW_H 0x08 23 #define REG_RTC_LOAD_VAL_L 0x0C 24 #define REG_RTC_LOAD_VAL_H 0x10 25 #define REG_RTC_MATCH_VAL_L 0x14 26 #define REG_RTC_MATCH_VAL_H 0x18 27 #define REG_RTC_STATUS_INT 0x1C 28 #define REG_RTC_CNT_VAL_L 0x20 29 #define REG_RTC_CNT_VAL_H 0x24 30 31 /* Control bits for REG_RTC_CTRL */ 32 #define SOFT_RSTZ_BIT BIT(0) 33 #define CNT_EN_BIT BIT(1) 34 #define WRAP_EN_BIT BIT(2) 35 #define LOAD_EN_BIT BIT(3) 36 #define READ_EN_BIT BIT(4) 37 #define INT_MASK_BIT BIT(5) 38 #define INT_FORCE_BIT BIT(6) 39 #define INT_CLEAR_BIT BIT(7) 40 41 /* Control bits for REG_RTC_STATUS_INT */ 42 #define RAW_INT_BIT BIT(0) 43 #define ALM_INT_BIT BIT(1) 44 45 struct msc313_rtc { 46 struct rtc_device *rtc_dev; 47 void __iomem *rtc_base; 48 }; 49 50 static int msc313_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm) 51 { 52 struct msc313_rtc *priv = dev_get_drvdata(dev); 53 unsigned long seconds; 54 55 seconds = readw(priv->rtc_base + REG_RTC_MATCH_VAL_L) 56 | ((unsigned long)readw(priv->rtc_base + REG_RTC_MATCH_VAL_H) << 16); 57 58 rtc_time64_to_tm(seconds, &alarm->time); 59 60 if (!(readw(priv->rtc_base + REG_RTC_CTRL) & INT_MASK_BIT)) 61 alarm->enabled = 1; 62 63 return 0; 64 } 65 66 static int msc313_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled) 67 { 68 struct msc313_rtc *priv = dev_get_drvdata(dev); 69 u16 reg; 70 71 reg = readw(priv->rtc_base + REG_RTC_CTRL); 72 if (enabled) 73 reg &= ~INT_MASK_BIT; 74 else 75 reg |= INT_MASK_BIT; 76 writew(reg, priv->rtc_base + REG_RTC_CTRL); 77 return 0; 78 } 79 80 static int msc313_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) 81 { 82 struct msc313_rtc *priv = dev_get_drvdata(dev); 83 unsigned long seconds; 84 85 seconds = rtc_tm_to_time64(&alarm->time); 86 writew((seconds & 0xFFFF), priv->rtc_base + REG_RTC_MATCH_VAL_L); 87 writew((seconds >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_MATCH_VAL_H); 88 89 msc313_rtc_alarm_irq_enable(dev, alarm->enabled); 90 91 return 0; 92 } 93 94 static bool msc313_rtc_get_enabled(struct msc313_rtc *priv) 95 { 96 return readw(priv->rtc_base + REG_RTC_CTRL) & CNT_EN_BIT; 97 } 98 99 static void msc313_rtc_set_enabled(struct msc313_rtc *priv) 100 { 101 u16 reg; 102 103 reg = readw(priv->rtc_base + REG_RTC_CTRL); 104 reg |= CNT_EN_BIT; 105 writew(reg, priv->rtc_base + REG_RTC_CTRL); 106 } 107 108 static int msc313_rtc_read_time(struct device *dev, struct rtc_time *tm) 109 { 110 struct msc313_rtc *priv = dev_get_drvdata(dev); 111 u32 seconds; 112 u16 reg; 113 114 if (!msc313_rtc_get_enabled(priv)) 115 return -EINVAL; 116 117 reg = readw(priv->rtc_base + REG_RTC_CTRL); 118 writew(reg | READ_EN_BIT, priv->rtc_base + REG_RTC_CTRL); 119 120 /* Wait for HW latch done */ 121 while (readw(priv->rtc_base + REG_RTC_CTRL) & READ_EN_BIT) 122 udelay(1); 123 124 seconds = readw(priv->rtc_base + REG_RTC_CNT_VAL_L) 125 | ((unsigned long)readw(priv->rtc_base + REG_RTC_CNT_VAL_H) << 16); 126 127 rtc_time64_to_tm(seconds, tm); 128 129 return 0; 130 } 131 132 static int msc313_rtc_set_time(struct device *dev, struct rtc_time *tm) 133 { 134 struct msc313_rtc *priv = dev_get_drvdata(dev); 135 unsigned long seconds; 136 u16 reg; 137 138 seconds = rtc_tm_to_time64(tm); 139 writew(seconds & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_L); 140 writew((seconds >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_H); 141 142 /* Enable load for loading value into internal RTC counter */ 143 reg = readw(priv->rtc_base + REG_RTC_CTRL); 144 writew(reg | LOAD_EN_BIT, priv->rtc_base + REG_RTC_CTRL); 145 146 /* Wait for HW latch done */ 147 while (readw(priv->rtc_base + REG_RTC_CTRL) & LOAD_EN_BIT) 148 udelay(1); 149 msc313_rtc_set_enabled(priv); 150 return 0; 151 } 152 153 static const struct rtc_class_ops msc313_rtc_ops = { 154 .read_time = msc313_rtc_read_time, 155 .set_time = msc313_rtc_set_time, 156 .read_alarm = msc313_rtc_read_alarm, 157 .set_alarm = msc313_rtc_set_alarm, 158 .alarm_irq_enable = msc313_rtc_alarm_irq_enable, 159 }; 160 161 static irqreturn_t msc313_rtc_interrupt(s32 irq, void *dev_id) 162 { 163 struct msc313_rtc *priv = dev_get_drvdata(dev_id); 164 u16 reg; 165 166 reg = readw(priv->rtc_base + REG_RTC_STATUS_INT); 167 if (!(reg & ALM_INT_BIT)) 168 return IRQ_NONE; 169 170 reg = readw(priv->rtc_base + REG_RTC_CTRL); 171 reg |= INT_CLEAR_BIT; 172 reg &= ~INT_FORCE_BIT; 173 writew(reg, priv->rtc_base + REG_RTC_CTRL); 174 175 rtc_update_irq(priv->rtc_dev, 1, RTC_IRQF | RTC_AF); 176 177 return IRQ_HANDLED; 178 } 179 180 static int msc313_rtc_probe(struct platform_device *pdev) 181 { 182 struct device *dev = &pdev->dev; 183 struct msc313_rtc *priv; 184 unsigned long rate; 185 struct clk *clk; 186 int ret; 187 int irq; 188 189 priv = devm_kzalloc(&pdev->dev, sizeof(struct msc313_rtc), GFP_KERNEL); 190 if (!priv) 191 return -ENOMEM; 192 193 priv->rtc_base = devm_platform_ioremap_resource(pdev, 0); 194 if (IS_ERR(priv->rtc_base)) 195 return PTR_ERR(priv->rtc_base); 196 197 irq = platform_get_irq(pdev, 0); 198 if (irq < 0) 199 return -EINVAL; 200 201 priv->rtc_dev = devm_rtc_allocate_device(dev); 202 if (IS_ERR(priv->rtc_dev)) 203 return PTR_ERR(priv->rtc_dev); 204 205 priv->rtc_dev->ops = &msc313_rtc_ops; 206 priv->rtc_dev->range_max = U32_MAX; 207 208 ret = devm_request_irq(dev, irq, msc313_rtc_interrupt, IRQF_SHARED, 209 dev_name(&pdev->dev), &pdev->dev); 210 if (ret) { 211 dev_err(dev, "Could not request IRQ\n"); 212 return ret; 213 } 214 215 clk = devm_clk_get(dev, NULL); 216 if (IS_ERR(clk)) { 217 dev_err(dev, "No input reference clock\n"); 218 return PTR_ERR(clk); 219 } 220 221 ret = clk_prepare_enable(clk); 222 if (ret) { 223 dev_err(dev, "Failed to enable the reference clock, %d\n", ret); 224 return ret; 225 } 226 227 ret = devm_add_action_or_reset(dev, (void (*) (void *))clk_disable_unprepare, clk); 228 if (ret) 229 return ret; 230 231 rate = clk_get_rate(clk); 232 writew(rate & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_L); 233 writew((rate >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_H); 234 235 platform_set_drvdata(pdev, priv); 236 237 return devm_rtc_register_device(priv->rtc_dev); 238 } 239 240 static const struct of_device_id msc313_rtc_of_match_table[] = { 241 { .compatible = "mstar,msc313-rtc" }, 242 { } 243 }; 244 MODULE_DEVICE_TABLE(of, msc313_rtc_of_match_table); 245 246 static struct platform_driver msc313_rtc_driver = { 247 .probe = msc313_rtc_probe, 248 .driver = { 249 .name = "msc313-rtc", 250 .of_match_table = msc313_rtc_of_match_table, 251 }, 252 }; 253 254 module_platform_driver(msc313_rtc_driver); 255 256 MODULE_AUTHOR("Daniel Palmer <daniel@thingy.jp>"); 257 MODULE_AUTHOR("Romain Perier <romain.perier@gmail.com>"); 258 MODULE_DESCRIPTION("MStar RTC Driver"); 259 MODULE_LICENSE("GPL v2"); 260