clk: imx: Fix reparenting of UARTs not associated with stdout

Most if not all i.MX SoC's call a function which enables all UARTS.
This is a problem for users who need to re-parent the clock source,
because any attempt to change the parent results in an busy error
due to the fact that the clocks have been enabled already.

  clk: failed to reparent uart1 to sys_pll1_80m: -16

Instead of pre-initializing all UARTS, scan the device tree to see
which UART clocks are associated to stdout, and only enable those
UART clocks if it's needed early.  This will move initialization of
the remaining clocks until after the parenting of the clocks.

When the clocks are shutdown, this mechanism will also disable any
clocks that were pre-initialized.

Fixes: 9461f7b33d11c ("clk: fix CLK_SET_RATE_GATE with clock rate protection")
Suggested-by: Aisheng Dong <aisheng.dong@nxp.com>
Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Abel Vesa <abel.vesa@nxp.com>
Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>

1 files changed, 3 insertions, 27 deletions

diff --git a/drivers/clk/imx/clk-imx5.c b/drivers/clk/imx/clk-imx5.c
index 01e079b81026..e4493846454d 100644
--- a/drivers/clk/imx/clk-imx5.c
+++ b/drivers/clk/imx/clk-imx5.c
@@ -128,30 +128,6 @@ static const char *ieee1588_sels[] = { "pll3_sw", "pll4_sw", "dummy" /* usbphy2_
 static struct clk *clk[IMX5_CLK_END];
 static struct clk_onecell_data clk_data;
 
-static struct clk ** const uart_clks_mx51[] __initconst = {
-	&clk[IMX5_CLK_UART1_IPG_GATE],
-	&clk[IMX5_CLK_UART1_PER_GATE],
-	&clk[IMX5_CLK_UART2_IPG_GATE],
-	&clk[IMX5_CLK_UART2_PER_GATE],
-	&clk[IMX5_CLK_UART3_IPG_GATE],
-	&clk[IMX5_CLK_UART3_PER_GATE],
-	NULL
-};
-
-static struct clk ** const uart_clks_mx50_mx53[] __initconst = {
-	&clk[IMX5_CLK_UART1_IPG_GATE],
-	&clk[IMX5_CLK_UART1_PER_GATE],
-	&clk[IMX5_CLK_UART2_IPG_GATE],
-	&clk[IMX5_CLK_UART2_PER_GATE],
-	&clk[IMX5_CLK_UART3_IPG_GATE],
-	&clk[IMX5_CLK_UART3_PER_GATE],
-	&clk[IMX5_CLK_UART4_IPG_GATE],
-	&clk[IMX5_CLK_UART4_PER_GATE],
-	&clk[IMX5_CLK_UART5_IPG_GATE],
-	&clk[IMX5_CLK_UART5_PER_GATE],
-	NULL
-};
-
 static void __init mx5_clocks_common_init(void __iomem *ccm_base)
 {
 	clk[IMX5_CLK_DUMMY]		= imx_clk_fixed("dummy", 0);
@@ -382,7 +358,7 @@ static void __init mx50_clocks_init(struct device_node *np)
 	r = clk_round_rate(clk[IMX5_CLK_USBOH3_PER_GATE], 54000000);
 	clk_set_rate(clk[IMX5_CLK_USBOH3_PER_GATE], r);
 
-	imx_register_uart_clocks(uart_clks_mx50_mx53);
+	imx_register_uart_clocks(5);
 }
 CLK_OF_DECLARE(imx50_ccm, "fsl,imx50-ccm", mx50_clocks_init);
 
@@ -488,7 +464,7 @@ static void __init mx51_clocks_init(struct device_node *np)
 	val |= 1 << 23;
 	writel(val, MXC_CCM_CLPCR);
 
-	imx_register_uart_clocks(uart_clks_mx51);
+	imx_register_uart_clocks(3);
 }
 CLK_OF_DECLARE(imx51_ccm, "fsl,imx51-ccm", mx51_clocks_init);
 
@@ -633,6 +609,6 @@ static void __init mx53_clocks_init(struct device_node *np)
 	r = clk_round_rate(clk[IMX5_CLK_USBOH3_PER_GATE], 54000000);
 	clk_set_rate(clk[IMX5_CLK_USBOH3_PER_GATE], r);
 
-	imx_register_uart_clocks(uart_clks_mx50_mx53);
+	imx_register_uart_clocks(5);
 }
 CLK_OF_DECLARE(imx53_ccm, "fsl,imx53-ccm", mx53_clocks_init);