diff mbox series

[v2,3/3] clk: samsung: gs101: propagate PERIC0 USI SPI clock rate

Message ID 20240326172813.801470-4-tudor.ambarus@linaro.org (mailing list archive)
State Superseded, archived
Headers show
Series clk: samsung: introduce nMUX to reparent MUX clocks | expand

Commit Message

Tudor Ambarus March 26, 2024, 5:28 p.m. UTC 
When SPI transfer is being prepared, the spi-s3c64xx driver will call
clk_set_rate() to change the rate of SPI source clock (IPCLK). But IPCLK
is a gate (leaf) clock, so it must propagate the rate change up the
clock tree, so that corresponding MUX/DIV clocks can actually change
their values. Add CLK_SET_RATE_PARENT flag to corresponding clocks for
all USI instances in GS101 PERIC0: USI{1-8, 14}. This change involves the
following clocks:

PERIC0 USI*:

    Clock                              Div range    MUX Selection
    -------------------------------------------------------------------
    gout_peric0_peric0_top0_ipclk_*    -            -
    dout_peric0_usi*_usi               /1..16       -
    mout_peric0_usi*_usi_user          -            {24.5 MHz, 400 MHz}

With input clock of 400 MHz this scheme provides the following IPCLK
rate range, for each USI block:

    PERIC0 USI*:       1.5 MHz ... 400 MHz

Accounting for internal /4 divider in SPI blocks, and because the max
SPI frequency is limited at 50 MHz, it gives us next SPI SCK rates:

    PERIC0 USI_SPI*:   384 KHz ... 49.9 MHz

Which shall be fine for the applications of the SPI bus.

Note that with this we allow the reparenting of the MUX_USIx clocks to
OSCCLK. Each instance of the USI IP has its own MUX_USI clock, thus the
reparenting of a MUX_USI clock corresponds to a single instance of the
USI IP. The datasheet mentions OSCCLK just in the low-power mode
context, but the downstream driver reparents too the MUX_USI clocks to
OSCCLK. Follow the downstream driver and do the same.

Fixes: 893f133a040b ("clk: samsung: gs101: add support for cmu_peric0")
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
---
 drivers/clk/samsung/clk-gs101.c | 135 +++++++++++++++++---------------
 1 file changed, 72 insertions(+), 63 deletions(-)

Comments

André Draszik March 28, 2024, 11:25 a.m. UTC | #1 
On Tue, 2024-03-26 at 17:28 +0000, Tudor Ambarus wrote:
> When SPI transfer is being prepared, the spi-s3c64xx driver will call
> clk_set_rate() to change the rate of SPI source clock (IPCLK). But IPCLK
> is a gate (leaf) clock, so it must propagate the rate change up the
> clock tree, so that corresponding MUX/DIV clocks can actually change
> their values. Add CLK_SET_RATE_PARENT flag to corresponding clocks for
> all USI instances in GS101 PERIC0: USI{1-8, 14}. This change involves the
> following clocks:
> 
> PERIC0 USI*:
> 
>     Clock                              Div range    MUX Selection
>     -------------------------------------------------------------------
>     gout_peric0_peric0_top0_ipclk_*    -            -
>     dout_peric0_usi*_usi               /1..16       -
>     mout_peric0_usi*_usi_user          -            {24.5 MHz, 400 MHz}
> 
> With input clock of 400 MHz this scheme provides the following IPCLK
> rate range, for each USI block:
> 
>     PERIC0 USI*:       1.5 MHz ... 400 MHz
> 
> Accounting for internal /4 divider in SPI blocks, and because the max
> SPI frequency is limited at 50 MHz, it gives us next SPI SCK rates:
> 
>     PERIC0 USI_SPI*:   384 KHz ... 49.9 MHz
> 
> Which shall be fine for the applications of the SPI bus.
> 
> Note that with this we allow the reparenting of the MUX_USIx clocks to
> OSCCLK. Each instance of the USI IP has its own MUX_USI clock, thus the
> reparenting of a MUX_USI clock corresponds to a single instance of the
> USI IP. The datasheet mentions OSCCLK just in the low-power mode
> context, but the downstream driver reparents too the MUX_USI clocks to
> OSCCLK. Follow the downstream driver and do the same.
> 
> Fixes: 893f133a040b ("clk: samsung: gs101: add support for cmu_peric0")
> Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>

Acked-by: André Draszik <andre.draszik@linaro.org>
Peter Griffin March 28, 2024, 11:36 a.m. UTC | #2 
Hi Tudor,

On Tue, 26 Mar 2024 at 17:28, Tudor Ambarus <tudor.ambarus@linaro.org> wrote:
>
> When SPI transfer is being prepared, the spi-s3c64xx driver will call
> clk_set_rate() to change the rate of SPI source clock (IPCLK). But IPCLK
> is a gate (leaf) clock, so it must propagate the rate change up the
> clock tree, so that corresponding MUX/DIV clocks can actually change
> their values. Add CLK_SET_RATE_PARENT flag to corresponding clocks for
> all USI instances in GS101 PERIC0: USI{1-8, 14}. This change involves the
> following clocks:
>
> PERIC0 USI*:
>
>     Clock                              Div range    MUX Selection
>     -------------------------------------------------------------------
>     gout_peric0_peric0_top0_ipclk_*    -            -
>     dout_peric0_usi*_usi               /1..16       -
>     mout_peric0_usi*_usi_user          -            {24.5 MHz, 400 MHz}
>
> With input clock of 400 MHz this scheme provides the following IPCLK
> rate range, for each USI block:
>
>     PERIC0 USI*:       1.5 MHz ... 400 MHz
>
> Accounting for internal /4 divider in SPI blocks, and because the max
> SPI frequency is limited at 50 MHz, it gives us next SPI SCK rates:
>
>     PERIC0 USI_SPI*:   384 KHz ... 49.9 MHz
>
> Which shall be fine for the applications of the SPI bus.
>
> Note that with this we allow the reparenting of the MUX_USIx clocks to
> OSCCLK. Each instance of the USI IP has its own MUX_USI clock, thus the
> reparenting of a MUX_USI clock corresponds to a single instance of the
> USI IP. The datasheet mentions OSCCLK just in the low-power mode
> context, but the downstream driver reparents too the MUX_USI clocks to
> OSCCLK. Follow the downstream driver and do the same.
>
> Fixes: 893f133a040b ("clk: samsung: gs101: add support for cmu_peric0")
> Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
> ---

Reviewed-by: Peter Griffin <peter.griffin@linaro.org>

regards,

Peter
diff mbox series

Patch

diff --git a/drivers/clk/samsung/clk-gs101.c b/drivers/clk/samsung/clk-gs101.c
index ddf2d57eed68..bd3c1b02715b 100644
--- a/drivers/clk/samsung/clk-gs101.c
+++ b/drivers/clk/samsung/clk-gs101.c
@@ -2763,33 +2763,33 @@  static const struct samsung_mux_clock peric0_mux_clks[] __initconst = {
 	MUX(CLK_MOUT_PERIC0_USI0_UART_USER,
 	    "mout_peric0_usi0_uart_user", mout_peric0_usi0_uart_user_p,
 	    PLL_CON0_MUX_CLKCMU_PERIC0_USI0_UART_USER, 4, 1),
-	MUX(CLK_MOUT_PERIC0_USI14_USI_USER,
-	    "mout_peric0_usi14_usi_user", mout_peric0_usi_usi_user_p,
-	    PLL_CON0_MUX_CLKCMU_PERIC0_USI14_USI_USER, 4, 1),
-	MUX(CLK_MOUT_PERIC0_USI1_USI_USER,
-	    "mout_peric0_usi1_usi_user", mout_peric0_usi_usi_user_p,
-	    PLL_CON0_MUX_CLKCMU_PERIC0_USI1_USI_USER, 4, 1),
-	MUX(CLK_MOUT_PERIC0_USI2_USI_USER,
-	    "mout_peric0_usi2_usi_user", mout_peric0_usi_usi_user_p,
-	    PLL_CON0_MUX_CLKCMU_PERIC0_USI2_USI_USER, 4, 1),
-	MUX(CLK_MOUT_PERIC0_USI3_USI_USER,
-	    "mout_peric0_usi3_usi_user", mout_peric0_usi_usi_user_p,
-	    PLL_CON0_MUX_CLKCMU_PERIC0_USI3_USI_USER, 4, 1),
-	MUX(CLK_MOUT_PERIC0_USI4_USI_USER,
-	    "mout_peric0_usi4_usi_user", mout_peric0_usi_usi_user_p,
-	    PLL_CON0_MUX_CLKCMU_PERIC0_USI4_USI_USER, 4, 1),
-	MUX(CLK_MOUT_PERIC0_USI5_USI_USER,
-	    "mout_peric0_usi5_usi_user", mout_peric0_usi_usi_user_p,
-	    PLL_CON0_MUX_CLKCMU_PERIC0_USI5_USI_USER, 4, 1),
-	MUX(CLK_MOUT_PERIC0_USI6_USI_USER,
-	    "mout_peric0_usi6_usi_user", mout_peric0_usi_usi_user_p,
-	    PLL_CON0_MUX_CLKCMU_PERIC0_USI6_USI_USER, 4, 1),
-	MUX(CLK_MOUT_PERIC0_USI7_USI_USER,
-	    "mout_peric0_usi7_usi_user", mout_peric0_usi_usi_user_p,
-	    PLL_CON0_MUX_CLKCMU_PERIC0_USI7_USI_USER, 4, 1),
-	MUX(CLK_MOUT_PERIC0_USI8_USI_USER,
-	    "mout_peric0_usi8_usi_user", mout_peric0_usi_usi_user_p,
-	    PLL_CON0_MUX_CLKCMU_PERIC0_USI8_USI_USER, 4, 1),
+	nMUX(CLK_MOUT_PERIC0_USI14_USI_USER,
+	     "mout_peric0_usi14_usi_user", mout_peric0_usi_usi_user_p,
+	     PLL_CON0_MUX_CLKCMU_PERIC0_USI14_USI_USER, 4, 1),
+	nMUX(CLK_MOUT_PERIC0_USI1_USI_USER,
+	     "mout_peric0_usi1_usi_user", mout_peric0_usi_usi_user_p,
+	     PLL_CON0_MUX_CLKCMU_PERIC0_USI1_USI_USER, 4, 1),
+	nMUX(CLK_MOUT_PERIC0_USI2_USI_USER,
+	     "mout_peric0_usi2_usi_user", mout_peric0_usi_usi_user_p,
+	     PLL_CON0_MUX_CLKCMU_PERIC0_USI2_USI_USER, 4, 1),
+	nMUX(CLK_MOUT_PERIC0_USI3_USI_USER,
+	     "mout_peric0_usi3_usi_user", mout_peric0_usi_usi_user_p,
+	     PLL_CON0_MUX_CLKCMU_PERIC0_USI3_USI_USER, 4, 1),
+	nMUX(CLK_MOUT_PERIC0_USI4_USI_USER,
+	     "mout_peric0_usi4_usi_user", mout_peric0_usi_usi_user_p,
+	     PLL_CON0_MUX_CLKCMU_PERIC0_USI4_USI_USER, 4, 1),
+	nMUX(CLK_MOUT_PERIC0_USI5_USI_USER,
+	     "mout_peric0_usi5_usi_user", mout_peric0_usi_usi_user_p,
+	     PLL_CON0_MUX_CLKCMU_PERIC0_USI5_USI_USER, 4, 1),
+	nMUX(CLK_MOUT_PERIC0_USI6_USI_USER,
+	     "mout_peric0_usi6_usi_user", mout_peric0_usi_usi_user_p,
+	     PLL_CON0_MUX_CLKCMU_PERIC0_USI6_USI_USER, 4, 1),
+	nMUX(CLK_MOUT_PERIC0_USI7_USI_USER,
+	     "mout_peric0_usi7_usi_user", mout_peric0_usi_usi_user_p,
+	     PLL_CON0_MUX_CLKCMU_PERIC0_USI7_USI_USER, 4, 1),
+	nMUX(CLK_MOUT_PERIC0_USI8_USI_USER,
+	     "mout_peric0_usi8_usi_user", mout_peric0_usi_usi_user_p,
+	     PLL_CON0_MUX_CLKCMU_PERIC0_USI8_USI_USER, 4, 1),
 };
 
 static const struct samsung_div_clock peric0_div_clks[] __initconst = {
@@ -2798,33 +2798,42 @@  static const struct samsung_div_clock peric0_div_clks[] __initconst = {
 	DIV(CLK_DOUT_PERIC0_USI0_UART,
 	    "dout_peric0_usi0_uart", "mout_peric0_usi0_uart_user",
 	    CLK_CON_DIV_DIV_CLK_PERIC0_USI0_UART, 0, 4),
-	DIV(CLK_DOUT_PERIC0_USI14_USI,
-	    "dout_peric0_usi14_usi", "mout_peric0_usi14_usi_user",
-	    CLK_CON_DIV_DIV_CLK_PERIC0_USI14_USI, 0, 4),
-	DIV(CLK_DOUT_PERIC0_USI1_USI,
-	    "dout_peric0_usi1_usi", "mout_peric0_usi1_usi_user",
-	    CLK_CON_DIV_DIV_CLK_PERIC0_USI1_USI, 0, 4),
-	DIV(CLK_DOUT_PERIC0_USI2_USI,
-	    "dout_peric0_usi2_usi", "mout_peric0_usi2_usi_user",
-	    CLK_CON_DIV_DIV_CLK_PERIC0_USI2_USI, 0, 4),
-	DIV(CLK_DOUT_PERIC0_USI3_USI,
-	    "dout_peric0_usi3_usi", "mout_peric0_usi3_usi_user",
-	    CLK_CON_DIV_DIV_CLK_PERIC0_USI3_USI, 0, 4),
-	DIV(CLK_DOUT_PERIC0_USI4_USI,
-	    "dout_peric0_usi4_usi", "mout_peric0_usi4_usi_user",
-	    CLK_CON_DIV_DIV_CLK_PERIC0_USI4_USI, 0, 4),
-	DIV(CLK_DOUT_PERIC0_USI5_USI,
-	    "dout_peric0_usi5_usi", "mout_peric0_usi5_usi_user",
-	    CLK_CON_DIV_DIV_CLK_PERIC0_USI5_USI, 0, 4),
-	DIV(CLK_DOUT_PERIC0_USI6_USI,
-	    "dout_peric0_usi6_usi", "mout_peric0_usi6_usi_user",
-	    CLK_CON_DIV_DIV_CLK_PERIC0_USI6_USI, 0, 4),
-	DIV(CLK_DOUT_PERIC0_USI7_USI,
-	    "dout_peric0_usi7_usi", "mout_peric0_usi7_usi_user",
-	    CLK_CON_DIV_DIV_CLK_PERIC0_USI7_USI, 0, 4),
-	DIV(CLK_DOUT_PERIC0_USI8_USI,
-	    "dout_peric0_usi8_usi", "mout_peric0_usi8_usi_user",
-	    CLK_CON_DIV_DIV_CLK_PERIC0_USI8_USI, 0, 4),
+	DIV_F(CLK_DOUT_PERIC0_USI14_USI,
+	      "dout_peric0_usi14_usi", "mout_peric0_usi14_usi_user",
+	      CLK_CON_DIV_DIV_CLK_PERIC0_USI14_USI, 0, 4,
+	      CLK_SET_RATE_PARENT, 0),
+	DIV_F(CLK_DOUT_PERIC0_USI1_USI,
+	      "dout_peric0_usi1_usi", "mout_peric0_usi1_usi_user",
+	      CLK_CON_DIV_DIV_CLK_PERIC0_USI1_USI, 0, 4,
+	      CLK_SET_RATE_PARENT, 0),
+	DIV_F(CLK_DOUT_PERIC0_USI2_USI,
+	      "dout_peric0_usi2_usi", "mout_peric0_usi2_usi_user",
+	      CLK_CON_DIV_DIV_CLK_PERIC0_USI2_USI, 0, 4,
+	      CLK_SET_RATE_PARENT, 0),
+	DIV_F(CLK_DOUT_PERIC0_USI3_USI,
+	      "dout_peric0_usi3_usi", "mout_peric0_usi3_usi_user",
+	      CLK_CON_DIV_DIV_CLK_PERIC0_USI3_USI, 0, 4,
+	      CLK_SET_RATE_PARENT, 0),
+	DIV_F(CLK_DOUT_PERIC0_USI4_USI,
+	      "dout_peric0_usi4_usi", "mout_peric0_usi4_usi_user",
+	      CLK_CON_DIV_DIV_CLK_PERIC0_USI4_USI, 0, 4,
+	      CLK_SET_RATE_PARENT, 0),
+	DIV_F(CLK_DOUT_PERIC0_USI5_USI,
+	      "dout_peric0_usi5_usi", "mout_peric0_usi5_usi_user",
+	      CLK_CON_DIV_DIV_CLK_PERIC0_USI5_USI, 0, 4,
+	      CLK_SET_RATE_PARENT, 0),
+	DIV_F(CLK_DOUT_PERIC0_USI6_USI,
+	      "dout_peric0_usi6_usi", "mout_peric0_usi6_usi_user",
+	      CLK_CON_DIV_DIV_CLK_PERIC0_USI6_USI, 0, 4,
+	      CLK_SET_RATE_PARENT, 0),
+	DIV_F(CLK_DOUT_PERIC0_USI7_USI,
+	      "dout_peric0_usi7_usi", "mout_peric0_usi7_usi_user",
+	      CLK_CON_DIV_DIV_CLK_PERIC0_USI7_USI, 0, 4,
+	      CLK_SET_RATE_PARENT, 0),
+	DIV_F(CLK_DOUT_PERIC0_USI8_USI,
+	      "dout_peric0_usi8_usi", "mout_peric0_usi8_usi_user",
+	      CLK_CON_DIV_DIV_CLK_PERIC0_USI8_USI, 0, 4,
+	      CLK_SET_RATE_PARENT, 0),
 };
 
 static const struct samsung_gate_clock peric0_gate_clks[] __initconst = {
@@ -2857,11 +2866,11 @@  static const struct samsung_gate_clock peric0_gate_clks[] __initconst = {
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_0,
 	     "gout_peric0_peric0_top0_ipclk_0", "dout_peric0_usi1_usi",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_IPCLK_0,
-	     21, 0, 0),
+	     21, CLK_SET_RATE_PARENT, 0),
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_1,
 	     "gout_peric0_peric0_top0_ipclk_1", "dout_peric0_usi2_usi",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_IPCLK_1,
-	     21, 0, 0),
+	     21, CLK_SET_RATE_PARENT, 0),
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_10,
 	     "gout_peric0_peric0_top0_ipclk_10", "dout_peric0_i3c",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_IPCLK_10,
@@ -2889,27 +2898,27 @@  static const struct samsung_gate_clock peric0_gate_clks[] __initconst = {
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_2,
 	     "gout_peric0_peric0_top0_ipclk_2", "dout_peric0_usi3_usi",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_IPCLK_2,
-	     21, 0, 0),
+	     21, CLK_SET_RATE_PARENT, 0),
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_3,
 	     "gout_peric0_peric0_top0_ipclk_3", "dout_peric0_usi4_usi",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_IPCLK_3,
-	     21, 0, 0),
+	     21, CLK_SET_RATE_PARENT, 0),
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_4,
 	     "gout_peric0_peric0_top0_ipclk_4", "dout_peric0_usi5_usi",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_IPCLK_4,
-	     21, 0, 0),
+	     21, CLK_SET_RATE_PARENT, 0),
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_5,
 	     "gout_peric0_peric0_top0_ipclk_5", "dout_peric0_usi6_usi",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_IPCLK_5,
-	     21, 0, 0),
+	     21, CLK_SET_RATE_PARENT, 0),
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_6,
 	     "gout_peric0_peric0_top0_ipclk_6", "dout_peric0_usi7_usi",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_IPCLK_6,
-	     21, 0, 0),
+	     21, CLK_SET_RATE_PARENT, 0),
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_7,
 	     "gout_peric0_peric0_top0_ipclk_7", "dout_peric0_usi8_usi",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_IPCLK_7,
-	     21, 0, 0),
+	     21, CLK_SET_RATE_PARENT, 0),
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_8,
 	     "gout_peric0_peric0_top0_ipclk_8", "dout_peric0_i3c",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_IPCLK_8,
@@ -2990,7 +2999,7 @@  static const struct samsung_gate_clock peric0_gate_clks[] __initconst = {
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP1_IPCLK_2,
 	     "gout_peric0_peric0_top1_ipclk_2", "dout_peric0_usi14_usi",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP1_IPCLKPORT_IPCLK_2,
-	     21, 0, 0),
+	     21, CLK_SET_RATE_PARENT, 0),
 	/* Disabling this clock makes the system hang. Mark the clock as critical. */
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP1_PCLK_0,
 	     "gout_peric0_peric0_top1_pclk_0", "mout_peric0_bus_user",