crypto: mxs-dcp - Add support for dcp clk

On 6ull and 6sll the DCP block has a clock which needs to be explicitly
enabled.

Add minimal handling for this at probe/remove time.

Signed-off-by: Leonard Crestez <[e-mail]>
Reviewed-by: Fabio Estevam <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/mxs-dcp.c

···
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/stmp_device.h>
+#include <linux/clk.h>
 
 #include <crypto/aes.h>
 #include <crypto/sha.h>
···
 	spinlock_t			lock[DCP_MAX_CHANS];
 	struct task_struct		*thread[DCP_MAX_CHANS];
 	struct crypto_queue		queue[DCP_MAX_CHANS];
+	struct clk			*dcp_clk;
 };
 
 enum dcp_chan {
···
 	/* Re-align the structure so it fits the DCP constraints. */
 	sdcp->coh = PTR_ALIGN(sdcp->coh, DCP_ALIGNMENT);
 
-	/* Restart the DCP block. */
-	ret = stmp_reset_block(sdcp->base);
+	/* DCP clock is optional, only used on some SOCs */
+	sdcp->dcp_clk = devm_clk_get(dev, "dcp");
+	if (IS_ERR(sdcp->dcp_clk)) {
+		if (sdcp->dcp_clk != ERR_PTR(-ENOENT))
+			return PTR_ERR(sdcp->dcp_clk);
+		sdcp->dcp_clk = NULL;
+	}
+	ret = clk_prepare_enable(sdcp->dcp_clk);
 	if (ret)
 		return ret;
+
+	/* Restart the DCP block. */
+	ret = stmp_reset_block(sdcp->base);
+	if (ret) {
+		dev_err(dev, "Failed reset\n");
+		goto err_disable_unprepare_clk;
+	}
 
 	/* Initialize control register. */
 	writel(MXS_DCP_CTRL_GATHER_RESIDUAL_WRITES |
···
 						      NULL, "mxs_dcp_chan/sha");
 	if (IS_ERR(sdcp->thread[DCP_CHAN_HASH_SHA])) {
 		dev_err(dev, "Error starting SHA thread!\n");
-		return PTR_ERR(sdcp->thread[DCP_CHAN_HASH_SHA]);
+		ret = PTR_ERR(sdcp->thread[DCP_CHAN_HASH_SHA]);
+		goto err_disable_unprepare_clk;
 	}
 
 	sdcp->thread[DCP_CHAN_CRYPTO] = kthread_run(dcp_chan_thread_aes,
···
 
 err_destroy_sha_thread:
 	kthread_stop(sdcp->thread[DCP_CHAN_HASH_SHA]);
+
+err_disable_unprepare_clk:
+	clk_disable_unprepare(sdcp->dcp_clk);
+
 	return ret;
 }
 
···
 
 	kthread_stop(sdcp->thread[DCP_CHAN_HASH_SHA]);
 	kthread_stop(sdcp->thread[DCP_CHAN_CRYPTO]);
+
+	clk_disable_unprepare(sdcp->dcp_clk);
 
 	platform_set_drvdata(pdev, NULL);