drivers/mfd/fsl-imx25-tsadc.c

   1 /*
   2  * Copyright (C) 2014-2015 Pengutronix, Markus Pargmann <mpa@pengutronix.de>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it under
   5  * the terms of the GNU General Public License version 2 as published by the
   6  * Free Software Foundation.
   7  */
   8
   9 #include <linux/clk.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/irqchip/chained_irq.h>
  12 #include <linux/irqdesc.h>
  13 #include <linux/irqdomain.h>
  14 #include <linux/irq.h>
  15 #include <linux/mfd/imx25-tsadc.h>
  16 #include <linux/module.h>
  17 #include <linux/of.h>
  18 #include <linux/of_platform.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/regmap.h>
  21
  22 static struct regmap_config mx25_tsadc_regmap_config = {
  23         .fast_io = true,
  24         .max_register = 8,
  25         .reg_bits = 32,
  26         .val_bits = 32,
  27         .reg_stride = 4,
  28 };
  29
  30 static void mx25_tsadc_irq_handler(struct irq_desc *desc)
  31 {
  32         struct mx25_tsadc *tsadc = irq_desc_get_handler_data(desc);
  33         struct irq_chip *chip = irq_desc_get_chip(desc);
  34         u32 status;
  35
  36         chained_irq_enter(chip, desc);
  37
  38         regmap_read(tsadc->regs, MX25_TSC_TGSR, &status);
  39
  40         if (status & MX25_TGSR_GCQ_INT)
  41                 generic_handle_irq(irq_find_mapping(tsadc->domain, 1));
  42
  43         if (status & MX25_TGSR_TCQ_INT)
  44                 generic_handle_irq(irq_find_mapping(tsadc->domain, 0));
  45
  46         chained_irq_exit(chip, desc);
  47 }
  48
  49 static int mx25_tsadc_domain_map(struct irq_domain *d, unsigned int irq,
  50                                  irq_hw_number_t hwirq)
  51 {
  52         struct mx25_tsadc *tsadc = d->host_data;
  53
  54         irq_set_chip_data(irq, tsadc);
  55         irq_set_chip_and_handler(irq, &dummy_irq_chip,
  56                                  handle_level_irq);
  57         irq_modify_status(irq, IRQ_NOREQUEST, IRQ_NOPROBE);
  58
  59         return 0;
  60 }
  61
  62 static struct irq_domain_ops mx25_tsadc_domain_ops = {
  63         .map = mx25_tsadc_domain_map,
  64         .xlate = irq_domain_xlate_onecell,
  65 };
  66
  67 static int mx25_tsadc_setup_irq(struct platform_device *pdev,
  68                                 struct mx25_tsadc *tsadc)
  69 {
  70         struct device *dev = &pdev->dev;
  71         struct device_node *np = dev->of_node;
  72         int irq;
  73
  74         irq = platform_get_irq(pdev, 0);
  75         if (irq <= 0) {
  76                 dev_err(dev, "Failed to get irq\n");
  77                 return irq;
  78         }
  79
  80         tsadc->domain = irq_domain_add_simple(np, 2, 0, &mx25_tsadc_domain_ops,
  81                                               tsadc);
  82         if (!tsadc->domain) {
  83                 dev_err(dev, "Failed to add irq domain\n");
  84                 return -ENOMEM;
  85         }
  86
  87         irq_set_chained_handler(irq, mx25_tsadc_irq_handler);
  88         irq_set_handler_data(irq, tsadc);
  89
  90         return 0;
  91 }
  92
  93 static void mx25_tsadc_setup_clk(struct platform_device *pdev,
  94                                  struct mx25_tsadc *tsadc)
  95 {
  96         unsigned clk_div;
  97
  98         /*
  99          * According to the datasheet the ADC clock should never
 100          * exceed 1,75 MHz. Base clock is the IPG and the ADC unit uses
 101          * a funny clock divider. To keep the ADC conversion time constant
 102          * adapt the ADC internal clock divider to the IPG clock rate.
 103          */
 104
 105         dev_dbg(&pdev->dev, "Found master clock at %lu Hz\n",
 106                 clk_get_rate(tsadc->clk));
 107
 108         clk_div = DIV_ROUND_UP(clk_get_rate(tsadc->clk), 1750000);
 109         dev_dbg(&pdev->dev, "Setting up ADC clock divider to %u\n", clk_div);
 110
 111         /* adc clock = IPG clock / (2 * div + 2) */
 112         clk_div -= 2;
 113         clk_div /= 2;
 114
 115         /*
 116          * the ADC clock divider changes its behaviour when values below 4
 117          * are used: it is fixed to "/ 10" in this case
 118          */
 119         clk_div = max_t(unsigned, 4, clk_div);
 120
 121         dev_dbg(&pdev->dev, "Resulting ADC conversion clock at %lu Hz\n",
 122                 clk_get_rate(tsadc->clk) / (2 * clk_div + 2));
 123
 124         regmap_update_bits(tsadc->regs, MX25_TSC_TGCR,
 125                            MX25_TGCR_ADCCLKCFG(0x1f),
 126                            MX25_TGCR_ADCCLKCFG(clk_div));
 127 }
 128
 129 static int mx25_tsadc_probe(struct platform_device *pdev)
 130 {
 131         struct device *dev = &pdev->dev;
 132         struct device_node *np = dev->of_node;
 133         struct mx25_tsadc *tsadc;
 134         struct resource *res;
 135         int ret;
 136         void __iomem *iomem;
 137
 138         tsadc = devm_kzalloc(dev, sizeof(*tsadc), GFP_KERNEL);
 139         if (!tsadc)
 140                 return -ENOMEM;
 141
 142         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 143         iomem = devm_ioremap_resource(dev, res);
 144         if (IS_ERR(iomem))
 145                 return PTR_ERR(iomem);
 146
 147         tsadc->regs = devm_regmap_init_mmio(dev, iomem,
 148                                             &mx25_tsadc_regmap_config);
 149         if (IS_ERR(tsadc->regs)) {
 150                 dev_err(dev, "Failed to initialize regmap\n");
 151                 return PTR_ERR(tsadc->regs);
 152         }
 153
 154         tsadc->clk = devm_clk_get(dev, "ipg");
 155         if (IS_ERR(tsadc->clk)) {
 156                 dev_err(dev, "Failed to get ipg clock\n");
 157                 return PTR_ERR(tsadc->clk);
 158         }
 159
 160         /* setup clock according to the datasheet */
 161         mx25_tsadc_setup_clk(pdev, tsadc);
 162
 163         /* Enable clock and reset the component */
 164         regmap_update_bits(tsadc->regs, MX25_TSC_TGCR, MX25_TGCR_CLK_EN,
 165                            MX25_TGCR_CLK_EN);
 166         regmap_update_bits(tsadc->regs, MX25_TSC_TGCR, MX25_TGCR_TSC_RST,
 167                            MX25_TGCR_TSC_RST);
 168
 169         /* Setup powersaving mode, but enable internal reference voltage */
 170         regmap_update_bits(tsadc->regs, MX25_TSC_TGCR, MX25_TGCR_POWERMODE_MASK,
 171                            MX25_TGCR_POWERMODE_SAVE);
 172         regmap_update_bits(tsadc->regs, MX25_TSC_TGCR, MX25_TGCR_INTREFEN,
 173                            MX25_TGCR_INTREFEN);
 174
 175         ret = mx25_tsadc_setup_irq(pdev, tsadc);
 176         if (ret)
 177                 return ret;
 178
 179         platform_set_drvdata(pdev, tsadc);
 180
 181         of_platform_populate(np, NULL, NULL, dev);
 182
 183         return 0;
 184 }
 185
 186 static const struct of_device_id mx25_tsadc_ids[] = {
 187         { .compatible = "fsl,imx25-tsadc" },
 188         { /* Sentinel */ }
 189 };
 190
 191 static struct platform_driver mx25_tsadc_driver = {
 192         .driver = {
 193                 .name = "mx25-tsadc",
 194                 .of_match_table = of_match_ptr(mx25_tsadc_ids),
 195         },
 196         .probe = mx25_tsadc_probe,
 197 };
 198 module_platform_driver(mx25_tsadc_driver);
 199
 200 MODULE_DESCRIPTION("MFD for ADC/TSC for Freescale mx25");
 201 MODULE_AUTHOR("Markus Pargmann <mpa@pengutronix.de>");
 202 MODULE_LICENSE("GPL v2");
 203 MODULE_ALIAS("platform:mx25-tsadc");