mtd: nand: atmel_nand: retrieve NFC clock

Retrieve the NFC clock to make sure it is enabled. Make that optional to ensure
compatibility with previous device trees but document it as mandatory so newer
device trees will include it.

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index 9c5f717bda54..d1e502f8dbd0 100644
--- a/drivers/mtd/nand/atmel_nand.c
+++ b/drivers/mtd/nand/atmel_nand.c
@@ -27,6 +27,7 @@
  *
  */
 
+#include <linux/clk.h>
 #include <linux/dma-mapping.h>
 #include <linux/slab.h>
 #include <linux/module.h>
@@ -96,6 +97,8 @@ struct atmel_nfc {
         bool                    use_nfc_sram;
         bool                    write_by_sram;
 
+        struct clk              *clk;
+
         bool                    is_initialized;
         struct completion       comp_ready;
         struct completion       comp_cmd_done;
@@ -2248,6 +2251,7 @@ static int atmel_nand_nfc_probe(struct platform_device *pdev)
 {
         struct atmel_nfc *nfc = &nand_nfc;
         struct resource *nfc_cmd_regs, *nfc_hsmc_regs, *nfc_sram;
+        int ret;
 
         nfc_cmd_regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
         nfc->base_cmd_regs = devm_ioremap_resource(&pdev->dev, nfc_cmd_regs);
@@ -2279,8 +2283,28 @@ static int atmel_nand_nfc_probe(struct platform_device *pdev)
         nfc_writel(nfc->hsmc_regs, IDR, 0xffffffff);
         nfc_readl(nfc->hsmc_regs, SR);  /* clear the NFC_SR */
 
+        nfc->clk = devm_clk_get(&pdev->dev, NULL);
+        if (!IS_ERR(nfc->clk)) {
+                ret = clk_prepare_enable(nfc->clk);
+                if (ret)
+                        return ret;
+        } else {
+                dev_warn(&pdev->dev, "NFC clock missing, update your Device Tree");
+        }
+
         nfc->is_initialized = true;
         dev_info(&pdev->dev, "NFC is probed.\n");
+
+        return 0;
+}
+
+static int atmel_nand_nfc_remove(struct platform_device *pdev)
+{
+        struct atmel_nfc *nfc = &nand_nfc;
+
+        if (!IS_ERR(nfc->clk))
+                clk_disable_unprepare(nfc->clk);
+
         return 0;
 }
 
@@ -2297,6 +2321,7 @@ static struct platform_driver atmel_nand_nfc_driver = {
                 .of_match_table = of_match_ptr(atmel_nand_nfc_match),
         },
         .probe = atmel_nand_nfc_probe,
+        .remove = atmel_nand_nfc_remove,
 };
 
 static struct platform_driver atmel_nand_driver = {