[PATCH 5.7 152/204] clk: bcm2835: Do not use prediv with bcm2711s PLLs

Greg Kroah-Hartman
2020-08-20T09:42:12Z

From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>

[ Upstream commit f34e4651ce66a754f41203284acf09b28b9dd955 ]

Contrary to previous SoCs, bcm2711 doesn't have a prescaler in the PLL
feedback loop. Bypass it by zeroing fb_prediv_mask when running on
bcm2711.

Note that, since the prediv configuration bits were re-purposed, this
was triggering miscalculations on all clocks hanging from the VPU clock,
notably the aux UART, making its output unintelligible.

Fixes: 42de9ad400af ("clk: bcm2835: Add BCM2711_CLOCK_EMMC2 support")
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/20200730182619.23246-1-nsaenzjulienne@suse.de
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/clk/bcm/clk-bcm2835.c | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 7c845c293af00..798f0b419c79f 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -314,6 +314,7 @@ struct bcm2835_cprman {
struct device *dev;
void __iomem *regs;
spinlock_t regs_lock; /* spinlock for all clocks */
+ unsigned int soc;

/*
* Real names of cprman clock parents looked up through
@@ -525,6 +526,20 @@ static int bcm2835_pll_is_on(struct clk_hw *hw)
A2W_PLL_CTRL_PRST_DISABLE;
}

+static u32 bcm2835_pll_get_prediv_mask(struct bcm2835_cprman *cprman,
+ const struct bcm2835_pll_data *data)
+{
+ /*
+ * On BCM2711 there isn't a pre-divisor available in the PLL feedback
+ * loop. Bits 13:14 of ANA1 (PLLA,PLLB,PLLC,PLLD) have been re-purposed
+ * for to for VCO RANGE bits.
+ */
+ if (cprman->soc & SOC_BCM2711)
+ return 0;
+
+ return data->ana->fb_prediv_mask;
+}
+
static void bcm2835_pll_choose_ndiv_and_fdiv(unsigned long rate,
unsigned long parent_rate,
u32 *ndiv, u32 *fdiv)
@@ -582,7 +597,7 @@ static unsigned long bcm2835_pll_get_rate(struct clk_hw *hw,
ndiv = (a2wctrl & A2W_PLL_CTRL_NDIV_MASK) >> A2W_PLL_CTRL_NDIV_SHIFT;
pdiv = (a2wctrl & A2W_PLL_CTRL_PDIV_MASK) >> A2W_PLL_CTRL_PDIV_SHIFT;
using_prediv = cprman_read(cprman, data->ana_reg_base + 4) &
- data->ana->fb_prediv_mask;
+ bcm2835_pll_get_prediv_mask(cprman, data);

if (using_prediv) {
ndiv *= 2;
@@ -665,6 +680,7 @@ static int bcm2835_pll_set_rate(struct clk_hw *hw,
struct bcm2835_pll *pll = container_of(hw, struct bcm2835_pll, hw);
struct bcm2835_cprman *cprman = pll->cprman;
const struct bcm2835_pll_data *data = pll->data;
+ u32 prediv_mask = bcm2835_pll_get_prediv_mask(cprman, data);
bool was_using_prediv, use_fb_prediv, do_ana_setup_first;
u32 ndiv, fdiv, a2w_ctl;
u32 ana[4];
@@ -682,7 +698,7 @@ static int bcm2835_pll_set_rate(struct clk_hw *hw,
for (i = 3; i >= 0; i--)
ana[i] = cprman_read(cprman, data->ana_reg_base + i * 4);

- was_using_prediv = ana[1] & data->ana->fb_prediv_mask;
+ was_using_prediv = ana[1] & prediv_mask;

ana[0] &= ~data->ana->mask0;
ana[0] |= data->ana->set0;
@@ -692,10 +708,10 @@ static int bcm2835_pll_set_rate(struct clk_hw *hw,
ana[3] |= data->ana->set3;

if (was_using_prediv && !use_fb_prediv) {
- ana[1] &= ~data->ana->fb_prediv_mask;
+ ana[1] &= ~prediv_mask;
do_ana_setup_first = true;
} else if (!was_using_prediv && use_fb_prediv) {
- ana[1] |= data->ana->fb_prediv_mask;
+ ana[1] |= prediv_mask;
do_ana_setup_first = false;
} else {
do_ana_setup_first = true;
@@ -2232,6 +2248,7 @@ static int bcm2835_clk_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, cprman);

cprman->onecell.num = asize;
+ cprman->soc = pdata->soc;
hws = cprman->onecell.hws;

for (i = 0; i < asize; i++) {
--
2.25.1