ARM: tegra: emc: convert tegra2_emc to a platform driver

This is the first step in making it device-tree aware and get rid of the
in-kernel EMC tables (of which there are none in mainline, thankfully).

Changes since v3:

* moved to devm_request_and_ioremap() in probe()

Changes since v2:

* D'oh -- missed a couple of variables that were added, never used and then
  later removed in a later patch.

Changes since v1:

* Fixed messed up indentation
* Removed code that should be gone (was added here and removed later in series)

Signed-off-by: Olof Johansson <olof@lixom.net>
Acked-by: Stephen Warren <swarren@nvidia.com>

2 files changed, 73 insertions, 30 deletions

diff --git a/arch/arm/mach-tegra/tegra2_emc.c b/arch/arm/mach-tegra/tegra2_emc.c
index 0f7ae6e90b55..e6229bbbb83a 100644
--- a/arch/arm/mach-tegra/tegra2_emc.c
+++ b/arch/arm/mach-tegra/tegra2_emc.c
@@ -16,10 +16,13 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/device.h>
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/tegra_emc.h>
 
 #include <mach/iomap.h>
 
@@ -32,18 +35,17 @@ static bool emc_enable;
 #endif
 module_param(emc_enable, bool, 0644);
 
-static void __iomem *emc = IO_ADDRESS(TEGRA_EMC_BASE);
-static const struct tegra_emc_table *tegra_emc_table;
-static int tegra_emc_table_size;
+static struct platform_device *emc_pdev;
+static void __iomem *emc_regbase;
 
 static inline void emc_writel(u32 val, unsigned long addr)
 {
-        writel(val, emc + addr);
+        writel(val, emc_regbase + addr);
 }
 
 static inline u32 emc_readl(unsigned long addr)
 {
-        return readl(emc + addr);
+        return readl(emc_regbase + addr);
 }
 
 static const unsigned long emc_reg_addr[TEGRA_EMC_NUM_REGS] = {
@@ -98,15 +100,15 @@ static const unsigned long emc_reg_addr[TEGRA_EMC_NUM_REGS] = {
 /* Select the closest EMC rate that is higher than the requested rate */
 long tegra_emc_round_rate(unsigned long rate)
 {
+        struct tegra_emc_pdata *pdata;
         int i;
         int best = -1;
         unsigned long distance = ULONG_MAX;
 
-        if (!tegra_emc_table)
+        if (!emc_pdev)
                 return -EINVAL;
 
-        if (!emc_enable)
-                return -EINVAL;
+        pdata = emc_pdev->dev.platform_data;
 
         pr_debug("%s: %lu\n", __func__, rate);
 
@@ -116,10 +118,10 @@ long tegra_emc_round_rate(unsigned long rate)
          */
         rate = rate / 2 / 1000;
 
-        for (i = 0; i < tegra_emc_table_size; i++) {
-                if (tegra_emc_table[i].rate >= rate &&
-                    (tegra_emc_table[i].rate - rate) < distance) {
-                        distance = tegra_emc_table[i].rate - rate;
+        for (i = 0; i < pdata->num_tables; i++) {
+                if (pdata->tables[i].rate >= rate &&
+                    (pdata->tables[i].rate - rate) < distance) {
+                        distance = pdata->tables[i].rate - rate;
                         best = i;
                 }
         }
@@ -127,9 +129,9 @@ long tegra_emc_round_rate(unsigned long rate)
         if (best < 0)
                 return -EINVAL;
 
-        pr_debug("%s: using %lu\n", __func__, tegra_emc_table[best].rate);
+        pr_debug("%s: using %lu\n", __func__, pdata->tables[best].rate);
 
-        return tegra_emc_table[best].rate * 2 * 1000;
+        return pdata->tables[best].rate * 2 * 1000;
 }
 
 /*
@@ -142,37 +144,81 @@ long tegra_emc_round_rate(unsigned long rate)
  */
 int tegra_emc_set_rate(unsigned long rate)
 {
+        struct tegra_emc_pdata *pdata;
         int i;
         int j;
 
-        if (!tegra_emc_table)
+        if (!emc_pdev)
                 return -EINVAL;
 
+        pdata = emc_pdev->dev.platform_data;
+
         /*
          * The EMC clock rate is twice the bus rate, and the bus rate is
          * measured in kHz
          */
         rate = rate / 2 / 1000;
 
-        for (i = 0; i < tegra_emc_table_size; i++)
-                if (tegra_emc_table[i].rate == rate)
+        for (i = 0; i < pdata->num_tables; i++)
+                if (pdata->tables[i].rate == rate)
                         break;
 
-        if (i >= tegra_emc_table_size)
+        if (i >= pdata->num_tables)
                 return -EINVAL;
 
         pr_debug("%s: setting to %lu\n", __func__, rate);
 
         for (j = 0; j < TEGRA_EMC_NUM_REGS; j++)
-                emc_writel(tegra_emc_table[i].regs[j], emc_reg_addr[j]);
+                emc_writel(pdata->tables[i].regs[j], emc_reg_addr[j]);
+
+        emc_readl(pdata->tables[i].regs[TEGRA_EMC_NUM_REGS - 1]);
+
+        return 0;
+}
+
+static int __devinit tegra_emc_probe(struct platform_device *pdev)
+{
+        struct tegra_emc_pdata *pdata;
+        struct resource *res;
+
+        if (!emc_enable) {
+                dev_err(&pdev->dev, "disabled per module parameter\n");
+                return -ENODEV;
+        }
+
+        pdata = pdev->dev.platform_data;
 
-        emc_readl(tegra_emc_table[i].regs[TEGRA_EMC_NUM_REGS - 1]);
+        if (!pdata) {
+                dev_err(&pdev->dev, "missing platform data\n");
+                return -ENXIO;
+        }
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (!res) {
+                dev_err(&pdev->dev, "missing register base\n");
+                return -ENOMEM;
+        }
+
+        emc_regbase = devm_request_and_ioremap(&pdev->dev, res);
+        if (!emc_regbase) {
+                dev_err(&pdev->dev, "failed to remap registers\n");
+                return -ENOMEM;
+        }
+        emc_pdev = pdev;
 
         return 0;
 }
 
-void tegra_init_emc(const struct tegra_emc_table *table, int table_size)
+static struct platform_driver tegra_emc_driver = {
+        .driver         = {
+                .name   = "tegra-emc",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = tegra_emc_probe,
+};
+
+static int __init tegra_emc_init(void)
 {
-        tegra_emc_table = table;
-        tegra_emc_table_size = table_size;
+        return platform_driver_register(&tegra_emc_driver);
 }
+device_initcall(tegra_emc_init);
diff --git a/arch/arm/mach-tegra/tegra2_emc.h b/arch/arm/mach-tegra/tegra2_emc.h
index 19f08cb31603..f61409b54cb7 100644
--- a/arch/arm/mach-tegra/tegra2_emc.h
+++ b/arch/arm/mach-tegra/tegra2_emc.h
@@ -15,13 +15,10 @@
  *
  */
 
-#define TEGRA_EMC_NUM_REGS 46
-
-struct tegra_emc_table {
-        unsigned long rate;
-        u32 regs[TEGRA_EMC_NUM_REGS];
-};
+#ifndef __MACH_TEGRA_TEGRA2_EMC_H_
+#define __MACH_TEGRA_TEGRA2_EMC_H
 
 int tegra_emc_set_rate(unsigned long rate);
 long tegra_emc_round_rate(unsigned long rate);
-void tegra_init_emc(const struct tegra_emc_table *table, int table_size);
+
+#endif