[ARM] S3C24XX: ADC driver core

A common core driver for the S3C24XX ADC block so that
the touchscreen, hwmon and any other drivers can share
the resource.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>

1 files changed, 372 insertions, 0 deletions

diff --git a/arch/arm/plat-s3c24xx/adc.c b/arch/arm/plat-s3c24xx/adc.c
new file mode 100644
index 000000000000..9a5c767e0a42
--- /dev/null
+++ b/arch/arm/plat-s3c24xx/adc.c
@@ -0,0 +1,372 @@
+/* arch/arm/plat-s3c24xx/adc.c
+ *
+ * Copyright (c) 2008 Simtec Electronics
+ *      http://armlinux.simtec.co.uk/
+ *      Ben Dooks <ben@simtec.co.uk>, <ben-linux@fluff.org>
+ *
+ * S3C24XX ADC device core
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License.
+*/
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/list.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+
+#include <plat/regs-adc.h>
+#include <plat/adc.h>
+
+/* This driver is designed to control the usage of the ADC block between
+ * the touchscreen and any other drivers that may need to use it, such as
+ * the hwmon driver.
+ *
+ * Priority will be given to the touchscreen driver, but as this itself is
+ * rate limited it should not starve other requests which are processed in
+ * order that they are received.
+ *
+ * Each user registers to get a client block which uniquely identifies it
+ * and stores information such as the necessary functions to callback when
+ * action is required.
+ */
+
+struct s3c_adc_client {
+        struct platform_device  *pdev;
+        struct list_head         pend;
+
+        unsigned int             nr_samples;
+        unsigned char            is_ts;
+        unsigned char            channel;
+
+        void    (*select_cb)(unsigned selected);
+        void    (*convert_cb)(unsigned val1, unsigned val2);
+};
+
+struct adc_device {
+        struct platform_device  *pdev;
+        struct platform_device  *owner;
+        struct clk              *clk;
+        struct s3c_adc_client   *cur;
+        struct s3c_adc_client   *ts_pend;
+        void __iomem            *regs;
+
+        unsigned int             prescale;
+
+        int                      irq;
+};
+
+static struct adc_device *adc_dev;
+
+static LIST_HEAD(adc_pending);
+
+#define adc_dbg(_adc, msg...) dev_dbg(&(_adc)->pdev->dev, msg)
+
+static inline void s3c_adc_convert(struct adc_device *adc)
+{
+        unsigned con = readl(adc->regs + S3C2410_ADCCON);
+
+        con |= S3C2410_ADCCON_ENABLE_START;
+        writel(con, adc->regs + S3C2410_ADCCON);
+}
+
+static inline void s3c_adc_select(struct adc_device *adc,
+                                  struct s3c_adc_client *client)
+{
+        unsigned con = readl(adc->regs + S3C2410_ADCCON);
+
+        client->select_cb(1);
+
+        con &= ~S3C2410_ADCCON_MUXMASK;
+        con &= ~S3C2410_ADCCON_STDBM;
+        con &= ~S3C2410_ADCCON_STARTMASK;
+
+        if (!client->is_ts)
+                con |= S3C2410_ADCCON_SELMUX(client->channel);
+
+        writel(con, adc->regs + S3C2410_ADCCON);
+}
+
+static void s3c_adc_dbgshow(struct adc_device *adc)
+{
+        adc_dbg(adc, "CON=%08x, TSC=%08x, DLY=%08x\n",
+                readl(adc->regs + S3C2410_ADCCON),
+                readl(adc->regs + S3C2410_ADCTSC),
+                readl(adc->regs + S3C2410_ADCDLY));
+}
+
+void s3c_adc_try(struct adc_device *adc)
+{
+        struct s3c_adc_client *next = adc->ts_pend;
+
+        if (!next && !list_empty(&adc_pending)) {
+                next = list_first_entry(&adc_pending,
+                                        struct s3c_adc_client, pend);
+                list_del(&next->pend);
+        } else
+                adc->ts_pend = NULL;
+
+        if (next) {
+                adc_dbg(adc, "new client is %p\n", next);
+                adc->cur = next;
+                s3c_adc_select(adc, next);
+                s3c_adc_convert(adc);
+                s3c_adc_dbgshow(adc);
+        }
+}
+
+int s3c_adc_start(struct s3c_adc_client *client,
+                  unsigned int channel, unsigned int nr_samples)
+{
+        struct adc_device *adc = adc_dev;
+        unsigned long flags;
+
+        if (!adc) {
+                printk(KERN_ERR "%s: failed to find adc\n", __func__);
+                return -EINVAL;
+        }
+
+        if (client->is_ts && adc->ts_pend)
+                return -EAGAIN;
+
+        local_irq_save(flags);
+
+        client->channel = channel;
+        client->nr_samples = nr_samples;
+
+        if (client->is_ts)
+                adc->ts_pend = client;
+        else
+                list_add_tail(&client->pend, &adc_pending);
+
+        if (!adc->cur)
+                s3c_adc_try(adc);
+        local_irq_restore(flags);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(s3c_adc_start);
+
+static void s3c_adc_default_select(unsigned select)
+{
+}
+
+struct s3c_adc_client *s3c_adc_register(struct platform_device *pdev,
+                                        void (*select)(unsigned int selected),
+                                        void (*conv)(unsigned d0, unsigned d1),
+                                        unsigned int is_ts)
+{
+        struct s3c_adc_client *client;
+
+        WARN_ON(!pdev);
+        WARN_ON(!conv);
+
+        if (!select)
+                select = s3c_adc_default_select;
+
+        if (!conv || !pdev)
+                return ERR_PTR(-EINVAL);
+
+        client = kzalloc(sizeof(struct s3c_adc_client), GFP_KERNEL);
+        if (!client) {
+                dev_err(&pdev->dev, "no memory for adc client\n");
+                return ERR_PTR(-ENOMEM);
+        }
+
+        client->pdev = pdev;
+        client->is_ts = is_ts;
+        client->select_cb = select;
+        client->convert_cb = conv;
+
+        return client;
+}
+EXPORT_SYMBOL_GPL(s3c_adc_register);
+
+void s3c_adc_release(struct s3c_adc_client *client)
+{
+        /* We should really check that nothing is in progress. */
+        kfree(client);
+}
+EXPORT_SYMBOL_GPL(s3c_adc_release);
+
+static irqreturn_t s3c_adc_irq(int irq, void *pw)
+{
+        struct adc_device *adc = pw;
+        struct s3c_adc_client *client = adc->cur;
+        unsigned long flags;
+        unsigned data0, data1;
+
+        if (!client) {
+                dev_warn(&adc->pdev->dev, "%s: no adc pending\n", __func__);
+                return IRQ_HANDLED;
+        }
+
+        data0 = readl(adc->regs + S3C2410_ADCDAT0);
+        data1 = readl(adc->regs + S3C2410_ADCDAT1);
+        adc_dbg(adc, "read %d: 0x%04x, 0x%04x\n", client->nr_samples, data0, data1);
+
+        (client->convert_cb)(data0 & 0x3ff, data1 & 0x3ff);
+
+        if (--client->nr_samples > 0) {
+                /* fire another conversion for this */
+
+                client->select_cb(1);
+                s3c_adc_convert(adc);
+        } else {
+                local_irq_save(flags);
+                (client->select_cb)(0);
+                adc->cur = NULL;
+
+                s3c_adc_try(adc);
+                local_irq_restore(flags);
+        }
+
+        return IRQ_HANDLED;
+}
+
+static int s3c_adc_probe(struct platform_device *pdev)
+{
+        struct device *dev = &pdev->dev;
+        struct adc_device *adc;
+        struct resource *regs;
+        int ret;
+
+        adc = kzalloc(sizeof(struct adc_device), GFP_KERNEL);
+        if (adc == NULL) {
+                dev_err(dev, "failed to allocate adc_device\n");
+                return -ENOMEM;
+        }
+
+        adc->pdev = pdev;
+        adc->prescale = S3C2410_ADCCON_PRSCVL(49);
+
+        adc->irq = platform_get_irq(pdev, 1);
+        if (adc->irq <= 0) {
+                dev_err(dev, "failed to get adc irq\n");
+                ret = -ENOENT;
+                goto err_alloc;
+        }
+
+        ret = request_irq(adc->irq, s3c_adc_irq, 0, dev_name(dev), adc);
+        if (ret < 0) {
+                dev_err(dev, "failed to attach adc irq\n");
+                goto err_alloc;
+        }
+
+        adc->clk = clk_get(dev, "adc");
+        if (IS_ERR(adc->clk)) {
+                dev_err(dev, "failed to get adc clock\n");
+                ret = PTR_ERR(adc->clk);
+                goto err_irq;
+        }
+
+        regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (!regs) {
+                dev_err(dev, "failed to find registers\n");
+                ret = -ENXIO;
+                goto err_clk;
+        }
+
+        adc->regs = ioremap(regs->start, resource_size(regs));
+        if (!adc->regs) {
+                dev_err(dev, "failed to map registers\n");
+                ret = -ENXIO;
+                goto err_clk;
+        }
+
+        clk_enable(adc->clk);
+
+        writel(adc->prescale | S3C2410_ADCCON_PRSCEN,
+               adc->regs + S3C2410_ADCCON);
+
+        dev_info(dev, "attached adc driver\n");
+
+        platform_set_drvdata(pdev, adc);
+        adc_dev = adc;
+
+        return 0;
+
+ err_clk:
+        clk_put(adc->clk);
+
+ err_irq:
+        free_irq(adc->irq, adc);
+
+ err_alloc:
+        kfree(adc);
+        return ret;
+}
+
+static int s3c_adc_remove(struct platform_device *pdev)
+{
+        struct adc_device *adc = platform_get_drvdata(pdev);
+
+        iounmap(adc->regs);
+        free_irq(adc->irq, adc);
+        clk_disable(adc->clk);
+        clk_put(adc->clk);
+        kfree(adc);
+
+        return 0;
+}
+
+#ifdef CONFIG_PM
+static int s3c_adc_suspend(struct platform_device *pdev, pm_message_t state)
+{
+        struct adc_device *adc = platform_get_drvdata(pdev);
+        u32 con;
+
+        con = readl(adc->regs + S3C2410_ADCCON);
+        con |= S3C2410_ADCCON_STDBM;
+        writel(con, adc->regs + S3C2410_ADCCON);
+
+        clk_disable(adc->clk);
+
+        return 0;
+}
+
+static int s3c_adc_resume(struct platform_device *pdev)
+{
+        struct adc_device *adc = platform_get_drvdata(pdev);
+
+        clk_enable(adc->clk);
+
+        writel(adc->prescale | S3C2410_ADCCON_PRSCEN,
+               adc->regs + S3C2410_ADCCON);
+
+        return 0;
+}
+
+#else
+#define s3c_adc_suspend NULL
+#define s3c_adc_resume NULL
+#endif
+
+static struct platform_driver s3c_adc_driver = {
+        .driver         = {
+                .name   = "s3c24xx-adc",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = s3c_adc_probe,
+        .remove         = __devexit_p(s3c_adc_remove),
+        .suspend        = s3c_adc_suspend,
+        .resume         = s3c_adc_resume,
+};
+
+static int __init adc_init(void)
+{
+        int ret;
+
+        ret = platform_driver_register(&s3c_adc_driver);
+        if (ret)
+                printk(KERN_ERR "%s: failed to add adc driver\n", __func__);
+
+        return ret;
+}
+
+arch_initcall(adc_init);